import { useMemo, useState } from "react";
import { Form, Link, redirect, useActionData, useNavigation } from "react-router";
import type { Route } from "./+types/admin.sports-seasons.$id.simulator";

import { AlertCircle, ArrowLeft, CheckCircle2, Loader2, Play, Save, SlidersHorizontal } from "lucide-react";
import { Badge } from "~/components/ui/badge";
import { Button } from "~/components/ui/button";
import { Input } from "~/components/ui/input";
import { Label } from "~/components/ui/label";
import {
  Card,
  CardContent,
  CardDescription,
  CardHeader,
  CardTitle,
} from "~/components/ui/card";
import { Textarea } from "~/components/ui/textarea";
import { findParticipantsBySportsSeasonId } from "~/models/season-participant";
import { findSportsSeasonById } from "~/models/sports-season";
import {
  batchUpsertParticipantSimulatorInputs,
  getParticipantSimulatorInputs,
  getSportsSeasonSimulatorConfig,
  upsertSportsSeasonSimulatorConfig,
  validateSimulatorReadiness,
  type UpsertParticipantSimulatorInput,
} from "~/models/simulator";
import { normalizeName } from "~/lib/fuzzy-match";
import {
  simulatorInputLabel,
  type SimulatorInputKey,
} from "~/services/simulations/manifest";
import {
  getSimulatorInputPolicy,
  resolveRatings,
  resolveSourceElos,
  type MissingEloStrategy,
  type MissingRatingStrategy,
  type ResolvedSourceElo,
} from "~/services/simulations/input-policy";
import { runSportsSeasonSimulation } from "~/services/simulations/runner";
import {
  parseBaseEloPriorityChoice,
  projectionMethodMetadata,
  resolvedInputMethodLabel,
} from "./admin.sports-seasons.$id.simulator.helpers";

export function meta({ data }: Route.MetaArgs): Route.MetaDescriptors {
  return [{ title: `Simulator Setup - ${data?.sportsSeason?.name ?? "Sports Season"} - Brackt Admin` }];
}

export async function loader({ params }: Route.LoaderArgs) {
  const sportsSeason = await findSportsSeasonById(params.id);
  if (!sportsSeason) {
    throw new Response("Sports season not found", { status: 404 });
  }

  const [participants, config, inputs, readiness] = await Promise.all([
    findParticipantsBySportsSeasonId(params.id),
    getSportsSeasonSimulatorConfig(params.id),
    getParticipantSimulatorInputs(params.id),
    validateSimulatorReadiness(params.id),
  ]);

  if (!config) {
    throw new Response("This sports season does not have a simulator configured.", { status: 404 });
  }

  const inputMap = new Map(inputs.map((input) => [input.participantId, input]));
  const inputRows = participants.map((participant) => ({
    participant,
    input: inputMap.get(participant.id) ?? null,
  }));

  const inputPolicy = getSimulatorInputPolicy(config.config);

  // The Elo each participant will actually run with, and which source produced it.
  // Without this the preview is misleading: getParticipantSimulatorInputs blanks a
  // generated Elo (so it is re-derived rather than frozen), which reads as "nothing
  // saved" — and a raw Elo silently beating a projection is invisible.
  const resolvedElos = config.profile.requiredInputs.includes("sourceElo")
    ? resolveSourceElos(inputs, config.profile, config.config)
    : new Map<string, ResolvedSourceElo>();
  const resolvedEloRows = Object.fromEntries(
    [...resolvedElos.values()].map((resolved) => [
      resolved.participantId,
      { sourceElo: resolved.sourceElo, method: resolved.method },
    ])
  );
  // Same for ratings, which are blanked by the same rule when generated. The
  // preview's "missing a required input" marker reads both, so it agrees with
  // readiness instead of flagging every participant a projection resolved.
  const resolvedRatingRows = Object.fromEntries(
    config.profile.requiredInputs.includes("rating")
      ? [...resolveRatings(inputs, config.profile, config.config).values()].map((resolved) => [
          resolved.participantId,
          { rating: resolved.rating, method: resolved.method },
        ])
      : []
  );

  // Sport-aware preview columns: the intersection of the displayable numeric keys
  // with this simulator's required + optional inputs, so each season shows exactly
  // the inputs its simulator consumes (F1 = odds, NBA = Elo, NCAA = rating, ...).
  // Resolved here (server-only) so the client bundle never imports the simulator
  // manifest/registry, which transitively pulls in `.server` modules.
  const relevantInputs = new Set<SimulatorInputKey>([
    ...config.profile.requiredInputs,
    ...config.profile.optionalInputs,
  ]);
  const inputColumns = DISPLAY_INPUT_ORDER.filter((key) => relevantInputs.has(key)).map((key) => ({
    key,
    label: simulatorInputLabel(key),
    required: config.profile.requiredInputs.includes(key),
  }));

  return {
    sportsSeason,
    participants,
    config,
    inputRows,
    readiness,
    inputPolicy,
    inputColumns,
    resolvedEloRows,
    resolvedRatingRows,
  };
}

interface ActionData {
  success?: boolean;
  message: string;
}

/**
 * Input keys the participant preview can render as a numeric column, in the order
 * they appear. Keys not listed (e.g. `region`, `metadata`) are not shown as
 * columns; the visible columns for a season are the intersection of this order
 * with the simulator's required + optional inputs.
 */
const DISPLAY_INPUT_ORDER: SimulatorInputKey[] = [
  "sourceElo",
  "sourceOdds",
  "worldRanking",
  "rating",
  "projectedWins",
  "projectedTablePoints",
  "seed",
];

const PARTICIPANT_PAGE_SIZE = 50;

/**
 * Engine knobs that a simulator (or the shared input-policy resolver) actually
 * reads from config. The structured Engine fields are limited to these so the UI
 * never shows a control that silently does nothing — bespoke per-sim constants
 * (e.g. homeFieldElo, eloDivisor, srsEloScale, raceNoise) that live in a profile
 * but are not read from config stay editable only via the raw-JSON escape hatch.
 */
const HONORED_ENGINE_KNOBS = new Set([
  "iterations",
  "parityFactor",
  "seasonGames",
  "overtimeRate",
  "matchParityFactor",
  "averageOpponentElo",
  "baseDrawRate",
  "drawDecay",
  "ratingScaleFactor",
  "projectedWinsWeight",
]);

function parseOptionalNumber(value: string | undefined): number | null {
  if (value === undefined || value.trim() === "") return null;
  const parsed = Number(value);
  return Number.isFinite(parsed) ? parsed : null;
}

function parsePolicyNumber(formData: FormData, key: string, fallback: number): number {
  const value = formData.get(key);
  if (typeof value !== "string" || value.trim() === "") return fallback;
  const parsed = Number(value);
  return Number.isFinite(parsed) ? parsed : fallback;
}

function parseMissingEloStrategy(value: FormDataEntryValue | null): MissingEloStrategy {
  return value === "fallbackElo" || value === "averageKnown" || value === "worstKnownMinus"
    ? value
    : "block";
}

function parseMissingRatingStrategy(value: FormDataEntryValue | null): MissingRatingStrategy {
  return value === "fallbackRating" || value === "averageKnown" || value === "worstKnownMinus"
    ? value
    : "block";
}

function findParticipantId(name: string, participants: Array<{ id: string; name: string }>): string | null {
  const normalizedInput = normalizeName(name);
  const normalized = participants.map((participant) => ({
    participant,
    normalized: normalizeName(participant.name),
  }));

  return (
    normalized.find((candidate) => candidate.normalized === normalizedInput)?.participant.id ??
    normalized.find((candidate) =>
      candidate.normalized.includes(normalizedInput) || normalizedInput.includes(candidate.normalized)
    )?.participant.id ??
    null
  );
}

const ODDS_LINE_PATTERN = /^(.+?)\s+([+-]\d{2,6})\s*$/;

function parseOddsLines(
  lines: string[],
  sportsSeasonId: string,
  participants: Array<{ id: string; name: string }>
): { inputs: UpsertParticipantSimulatorInput[]; unmatched: string[] } {
  const inputs: UpsertParticipantSimulatorInput[] = [];
  const unmatched: string[] = [];
  const seen = new Set<string>();

  for (const line of lines) {
    const match = ODDS_LINE_PATTERN.exec(line);
    if (!match) continue;

    const name = match[1].trim();
    const sourceOdds = Number(match[2]);
    if (!Number.isFinite(sourceOdds)) continue;

    const participantId = findParticipantId(name, participants);
    if (!participantId) {
      unmatched.push(name);
      continue;
    }
    if (seen.has(participantId)) continue;
    seen.add(participantId);

    inputs.push({ participantId, sportsSeasonId, sourceOdds });
  }

  return { inputs, unmatched };
}

function parseInputCsv(
  text: string,
  sportsSeasonId: string,
  participants: Array<{ id: string; name: string }>
): { inputs: UpsertParticipantSimulatorInput[]; unmatched: string[] } {
  const lines = text.split(/\r?\n/).map((line) => line.trim()).filter(Boolean);
  if (lines.length === 0) return { inputs: [], unmatched: [] };

  const header = lines[0].split(",").map((value) => value.trim());
  const indexes = new Map(header.map((value, index) => [value, index]));
  const nameIndex = indexes.get("name");
  if (nameIndex === undefined) {
    // No CSV header — treat the paste as sportsbook futures odds, one team per
    // line ending in American odds (e.g. `Kansas City Chiefs +450`). This is the
    // friendly bulk-futures path; team names are fuzzy-matched to participants.
    return parseOddsLines(lines, sportsSeasonId, participants);
  }

  const inputs: UpsertParticipantSimulatorInput[] = [];
  const unmatched: string[] = [];

  for (const line of lines.slice(1)) {
    const cols = line.split(",").map((value) => value.trim());
    const name = cols[nameIndex];
    if (!name) continue;

    const participantId = findParticipantId(name, participants);
    if (!participantId) {
      unmatched.push(name);
      continue;
    }

    const sourceElo = parseOptionalNumber(cols[indexes.get("sourceElo") ?? -1]) ?? undefined;
    const projectedWins = parseOptionalNumber(cols[indexes.get("projectedWins") ?? -1]) ?? undefined;
    const projectedTablePoints = parseOptionalNumber(cols[indexes.get("projectedTablePoints") ?? -1]) ?? undefined;

    inputs.push({
      participantId,
      sportsSeasonId,
      sourceElo,
      sourceOdds: parseOptionalNumber(cols[indexes.get("sourceOdds") ?? -1]) ?? undefined,
      worldRanking: parseOptionalNumber(cols[indexes.get("worldRanking") ?? -1]) ?? undefined,
      rating: parseOptionalNumber(cols[indexes.get("rating") ?? -1]) ?? undefined,
      projectedWins,
      projectedTablePoints,
      seed: parseOptionalNumber(cols[indexes.get("seed") ?? -1]) ?? undefined,
      region: cols[indexes.get("region") ?? -1] || undefined,
      // A row that supplies a projection but no explicit Elo means "derive the Elo
      // from this projection". Stamping the method flag marks whatever Elo is
      // already stored as generated, so getParticipantSimulatorInputs hides it and
      // resolveSourceElos re-derives from the projection instead of letting a stale
      // Elo win the baseEloPriority race. Mirrors the Elo Ratings page's
      // projections mode.
      metadata: projectionMethodMetadata(sourceElo, projectedWins, projectedTablePoints),
    });
  }

  return { inputs, unmatched };
}

export async function action({ request, params }: Route.ActionArgs): Promise<ActionData | Response> {
  const formData = await request.formData();
  const intent = formData.get("intent");
  const sportsSeasonId = params.id;

  if (intent === "run") {
    try {
      await runSportsSeasonSimulation(sportsSeasonId);
      return redirect(`/admin/sports-seasons/${sportsSeasonId}/expected-values`);
    } catch (error) {
      return { success: false, message: error instanceof Error ? error.message : "Simulation failed." };
    }
  }

  if (intent === "save-config") {
    const rawConfig = formData.get("config");
    const currentConfig = await getSportsSeasonSimulatorConfig(sportsSeasonId);
    if (!currentConfig) return { success: false, message: "Simulator config not found." };

    try {
      const parsed = typeof rawConfig === "string" && rawConfig.trim()
        ? JSON.parse(rawConfig) as Record<string, unknown>
        : {};
      // Preserve an existing inputPolicy if the submitted JSON omits it, so
      // editing other config keys doesn't silently wipe a previously configured
      // missing-Elo strategy.
      const config = "inputPolicy" in parsed
        ? parsed
        : { ...parsed, ...(currentConfig.config.inputPolicy !== undefined ? { inputPolicy: currentConfig.config.inputPolicy } : {}) };
      await upsertSportsSeasonSimulatorConfig({
        sportsSeasonId,
        simulatorType: currentConfig.simulatorType,
        config,
      });
      return { success: true, message: "Simulator config saved." };
    } catch (error) {
      return { success: false, message: error instanceof Error ? error.message : "Invalid config JSON." };
    }
  }

  if (intent === "save-configuration") {
    const currentConfig = await getSportsSeasonSimulatorConfig(sportsSeasonId);
    if (!currentConfig) return { success: false, message: "Simulator config not found." };

    // Start from the current merged config so keys not exposed as structured
    // fields (e.g. string knobs) are preserved untouched.
    const next: Record<string, unknown> = { ...currentConfig.config };

    // Engine knobs: every numeric field rendered as `engine.<key>`.
    for (const [field, value] of formData.entries()) {
      if (typeof value !== "string" || !field.startsWith("engine.")) continue;
      const key = field.slice("engine.".length);
      const parsed = Number(value);
      if (value.trim() !== "" && Number.isFinite(parsed)) next[key] = parsed;
    }

    // Input-derivation policy (only when the simulator consumes Elo/ratings).
    if (formData.get("hasInputPolicy") === "1") {
      const currentPolicy = getSimulatorInputPolicy(currentConfig.config);
      next.inputPolicy = {
        ...currentPolicy,
        missingEloStrategy: parseMissingEloStrategy(formData.get("missingEloStrategy")),
        missingRatingStrategy: parseMissingRatingStrategy(formData.get("missingRatingStrategy")),
        baseEloPriority: parseBaseEloPriorityChoice(formData.get("baseEloPriority"), currentPolicy.baseEloPriority),
        // Stored as-is; getSimulatorInputPolicy clamps to [0,1] on read.
        oddsWeight: parsePolicyNumber(formData, "oddsWeight", currentPolicy.oddsWeight),
        fallbackElo: parsePolicyNumber(formData, "fallbackElo", currentPolicy.fallbackElo),
        fallbackEloDelta: parsePolicyNumber(formData, "fallbackEloDelta", currentPolicy.fallbackEloDelta),
        eloMin: parsePolicyNumber(formData, "eloMin", currentPolicy.eloMin),
        eloMax: parsePolicyNumber(formData, "eloMax", currentPolicy.eloMax),
        fallbackRating: parsePolicyNumber(formData, "fallbackRating", currentPolicy.fallbackRating),
        fallbackRatingDelta: parsePolicyNumber(formData, "fallbackRatingDelta", currentPolicy.fallbackRatingDelta),
        ratingMin: parsePolicyNumber(formData, "ratingMin", currentPolicy.ratingMin),
        ratingMax: parsePolicyNumber(formData, "ratingMax", currentPolicy.ratingMax),
      };
    }

    await upsertSportsSeasonSimulatorConfig({
      sportsSeasonId,
      simulatorType: currentConfig.simulatorType,
      config: next,
    });
    return { success: true, message: "Simulator configuration saved." };
  }

  if (intent === "save-inputs") {
    const rawInputs = formData.get("bulkInputs");
    if (typeof rawInputs !== "string" || rawInputs.trim() === "") {
      return { success: false, message: "Paste at least one input row before saving." };
    }

    const participants = await findParticipantsBySportsSeasonId(sportsSeasonId);
    try {
      const parsed = parseInputCsv(rawInputs, sportsSeasonId, participants);
      if (parsed.inputs.length === 0) {
        return { success: false, message: "No matching participants found in the pasted inputs." };
      }
      await batchUpsertParticipantSimulatorInputs(parsed.inputs);
      const suffix = parsed.unmatched.length > 0
        ? ` ${parsed.unmatched.length} row(s) were unmatched: ${parsed.unmatched.join(", ")}.`
        : "";
      const saved = `Saved ${parsed.inputs.length} simulator input row(s).${suffix}`;

      // Auto-run the simulation so saved inputs immediately drive the standings.
      // The save itself already succeeded, so a run that never started (e.g.
      // participants missing required inputs) is reported as success with the
      // readiness gap — never as a failed save.
      try {
        await runSportsSeasonSimulation(sportsSeasonId);
        return redirect(`/admin/sports-seasons/${sportsSeasonId}/expected-values`);
      } catch (runError) {
        const reason = runError instanceof Error ? runError.message : "could not run.";
        // Distinguish "saved but never ran" (readiness/already-running) from
        // "started running and failed mid-run": the runner only flips the season
        // to status 'failed' once the simulation itself throws.
        const season = await findSportsSeasonById(sportsSeasonId);
        if (season?.simulationStatus === "failed") {
          return { success: false, message: `${saved} The simulation failed: ${reason}` };
        }
        return { success: true, message: `${saved} Simulation not run yet: ${reason}` };
      }
    } catch (error) {
      return { success: false, message: error instanceof Error ? error.message : "Failed to save simulator inputs." };
    }
  }

  return { success: false, message: "Unknown simulator setup action." };
}

export default function AdminSportsSeasonSimulator({ loaderData }: Route.ComponentProps) {
  const { sportsSeason, config, inputRows, readiness, inputPolicy } = loaderData;
  const actionData = useActionData<ActionData>();
  const navigation = useNavigation();
  const isSubmitting = navigation.state === "submitting";
  const setupSections = config.profile.setupSections;
  const sourceEloAlternatives = config.profile.derivableInputs?.sourceElo ?? [];
  // The projection key this simulator can derive Elo from (wins or table points),
  // or null when it has none — the base-priority control only makes sense with one.
  const projectionEloKey =
    sourceEloAlternatives.find((key) => key === "projectedWins" || key === "projectedTablePoints") ?? null;
  const projectionsOutrankElo = inputPolicy.baseEloPriority[0] !== "sourceElo";
  const ratingAlternatives = config.profile.derivableInputs?.rating ?? [];
  const showsInputPolicy =
    config.profile.requiredInputs.includes("sourceElo") || config.profile.requiredInputs.includes("rating");

  // Structured engine knobs: every top-level numeric config key (inputPolicy is a
  // nested object edited in its own section). Driving the fields from the merged
  // config means each simulator shows exactly the knobs it actually reads.
  const engineEntries = Object.entries(config.config)
    .filter(([key, value]) => HONORED_ENGINE_KNOBS.has(key) && typeof value === "number")
    .map(([key, value]) => [key, value as unknown as number] as [string, number]);

  // Preview columns are resolved server-side in the loader (see note there) and
  // arrive as plain data, so this client component never imports the manifest.
  const { inputColumns, resolvedEloRows, resolvedRatingRows } = loaderData;
  const requiredInputs = config.profile.requiredInputs;
  const gridTemplate = `2fr repeat(${Math.max(inputColumns.length, 1)}, 1fr)`;
  // For this sport the inputs live on a dedicated page, not the shared bulk paste.
  const externalInputsSection = requiredInputs.length === 0
    ? (setupSections.includes("surfaceElo")
        ? { label: "Surface Elo", to: `/admin/sports-seasons/${sportsSeason.id}/surface-elo` }
        : setupSections.includes("golfSkills")
          ? { label: "Golf Skills", to: `/admin/sports-seasons/${sportsSeason.id}/golf-skills` }
          : null)
    : null;

  // A required Elo/rating counts as present when the input policy resolves one,
  // not only when it is stored directly: getParticipantSimulatorInputs deliberately
  // blanks a generated value so it is re-derived each run, so reading the raw input
  // alone would mark every projection-configured participant as missing.
  const isRowIncomplete = (participantId: string, input: (typeof inputRows)[number]["input"]) =>
    requiredInputs.some((key) => {
      if (input?.[key] !== null && input?.[key] !== undefined) return false;
      if (key === "sourceElo") return resolvedEloRows[participantId] === undefined;
      if (key === "rating") return resolvedRatingRows[participantId] === undefined;
      return true;
    });

  const [search, setSearch] = useState("");
  const [onlyMissing, setOnlyMissing] = useState(false);
  const [page, setPage] = useState(0);

  const filteredRows = useMemo(() => {
    const normalizedSearch = normalizeName(search);
    return inputRows.filter(({ participant, input }) => {
      if (normalizedSearch && !normalizeName(participant.name).includes(normalizedSearch)) return false;
      if (onlyMissing && !isRowIncomplete(participant.id, input)) return false;
      return true;
    });
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [inputRows, search, onlyMissing, requiredInputs, resolvedEloRows, resolvedRatingRows]);

  const totalPages = Math.max(1, Math.ceil(filteredRows.length / PARTICIPANT_PAGE_SIZE));
  const safePage = Math.min(page, totalPages - 1);
  const pageStart = safePage * PARTICIPANT_PAGE_SIZE;
  const pageRows = filteredRows.slice(pageStart, pageStart + PARTICIPANT_PAGE_SIZE);

  return (
    <div className="container mx-auto p-6 space-y-6">
      <div className="flex items-center gap-4">
        <Button variant="ghost" size="sm" asChild>
          <Link to={`/admin/sports-seasons/${sportsSeason.id}`}>
            <ArrowLeft className="h-4 w-4 mr-2" />
            Back to Sports Season
          </Link>
        </Button>
        <Button variant="ghost" size="sm" asChild>
          <Link to="/admin/simulators">All Simulators</Link>
        </Button>
      </div>

      <div>
        <h1 className="text-3xl font-bold flex items-center gap-2">
          <SlidersHorizontal className="h-7 w-7" />
          Simulator Setup
        </h1>
        <p className="text-muted-foreground mt-1">
          {sportsSeason.sport.name} - {sportsSeason.name}
        </p>
      </div>

      {actionData && (
        <Card className={actionData.success ? "border-emerald-500/40" : "border-destructive/40"}>
          <CardContent className="py-4 text-sm">{actionData.message}</CardContent>
        </Card>
      )}

      <Card>
        <CardHeader>
          <div className="flex items-center justify-between gap-4">
            <div>
              <CardTitle>{config.profile.displayName}</CardTitle>
              <CardDescription>{config.profile.description}</CardDescription>
            </div>
            {readiness.status === "ready" ? (
              <Badge className="gap-1"><CheckCircle2 className="h-3 w-3" /> Ready</Badge>
            ) : (
              <Badge variant="secondary" className="gap-1"><AlertCircle className="h-3 w-3" /> Needs setup</Badge>
            )}
          </div>
        </CardHeader>
        <CardContent className="space-y-4">
          <div className="grid gap-3 md:grid-cols-3">
            <div className="rounded-md border p-3">
              <div className="text-sm text-muted-foreground">Simulator Type</div>
              <code className="text-sm">{config.simulatorType}</code>
            </div>
            <div className="rounded-md border p-3">
              <div className="text-sm text-muted-foreground">Participant Inputs</div>
              <div className="font-medium">{readiness.participantInputCount}/{readiness.participantCount}</div>
            </div>
            <div className="rounded-md border p-3">
              <div className="text-sm text-muted-foreground">Simulation Status</div>
              <div className="font-medium">{sportsSeason.simulationStatus}</div>
            </div>
          </div>

          {readiness.missingInputs.length > 0 && (
            <div className="rounded-md border border-amber-500/30 bg-amber-500/10 p-3 text-sm">
              Missing: {readiness.missingInputs.join(", ")}
            </div>
          )}

          {readiness.warnings.length > 0 && (
            <div className="rounded-md border border-sky-500/30 bg-sky-500/10 p-3 text-sm">
              {readiness.warnings.join(" ")}
            </div>
          )}

          <div className="flex flex-wrap gap-2">
            {setupSections.includes("eloRatings") &&<Button variant="outline" size="sm" asChild><Link to={`/admin/sports-seasons/${sportsSeason.id}/elo-ratings`}>Elo Ratings</Link></Button>}
            {setupSections.includes("surfaceElo") && <Button variant="outline" size="sm" asChild><Link to={`/admin/sports-seasons/${sportsSeason.id}/surface-elo`}>Surface Elo</Link></Button>}
            {setupSections.includes("golfSkills") && <Button variant="outline" size="sm" asChild><Link to={`/admin/sports-seasons/${sportsSeason.id}/golf-skills`}>Golf Skills</Link></Button>}
            {setupSections.includes("regularStandings") && <Button variant="outline" size="sm" asChild><Link to={`/admin/sports-seasons/${sportsSeason.id}/regular-standings`}>Regular Standings</Link></Button>}
            {setupSections.includes("events") && <Button variant="outline" size="sm" asChild><Link to={`/admin/sports-seasons/${sportsSeason.id}/events`}>Events</Link></Button>}
            <Button variant="outline" size="sm" asChild><Link to={`/admin/sports-seasons/${sportsSeason.id}/expected-values`}>Expected Values</Link></Button>
          </div>

          <Form method="post">
            <input type="hidden" name="intent" value="run" />
            <Button type="submit" disabled={!readiness.canRun || sportsSeason.simulationStatus === "running" || isSubmitting}>
              {isSubmitting ? <Loader2 className="mr-2 h-4 w-4 animate-spin" /> : <Play className="mr-2 h-4 w-4" />}
              Run Simulation
            </Button>
          </Form>
        </CardContent>
      </Card>

      <Card>
        <CardHeader>
          <CardTitle>Simulator Configuration</CardTitle>
          <CardDescription>
            One place for this season's settings. <strong>Engine</strong> controls how the Monte Carlo
            runs; <strong>Input derivation</strong> controls how raw inputs become the single Elo/rating
            the engine consumes. Defaults come from the simulator profile; values set here override them
            for this season only. Both sections write the same stored config.
          </CardDescription>
        </CardHeader>
        <CardContent className="space-y-6">
          <Form method="post" className="space-y-6">
            <input type="hidden" name="intent" value="save-configuration" />
            {showsInputPolicy && <input type="hidden" name="hasInputPolicy" value="1" />}

            <section className="space-y-3">
              <div>
                <h3 className="text-sm font-semibold">Engine</h3>
                <p className="text-xs text-muted-foreground">
                  How the simulation runs. A higher <code>parityFactor</code> flattens the finish-position
                  distribution (favorites win less often); <code>iterations</code> trades speed for precision.
                </p>
              </div>
              {engineEntries.length > 0 ? (
                <div className="grid gap-4 md:grid-cols-3">
                  {engineEntries.map(([key, value]) => (
                    <div key={key} className="space-y-2">
                      <Label htmlFor={`engine.${key}`} className="font-mono text-xs">{key}</Label>
                      <Input id={`engine.${key}`} name={`engine.${key}`} type="number" step="any" defaultValue={value} />
                    </div>
                  ))}
                </div>
              ) : (
                <p className="text-xs text-muted-foreground">This simulator exposes no numeric engine knobs.</p>
              )}
            </section>

            {showsInputPolicy && (
              <section className="space-y-3">
                <div>
                  <h3 className="text-sm font-semibold">Input derivation</h3>
                  <p className="text-xs text-muted-foreground">
                    Direct inputs win. This simulator can derive Elo from{" "}
                    {sourceEloAlternatives.length > 0 ? sourceEloAlternatives.join(", ") : "no alternate Elo inputs"}
                    {ratingAlternatives.length > 0 ? ` and ratings from ${ratingAlternatives.join(", ")}` : ""}.
                    Tail fallbacks are explicit so low-impact missing participants do not silently get invented ratings.
                  </p>
                </div>
                <div className="grid gap-4 md:grid-cols-5">
                  <div className="space-y-2 md:col-span-5">
                    <Label htmlFor="oddsWeight">Futures vs. Elo — Odds Blend Weight (0–1)</Label>
                    <Input id="oddsWeight" name="oddsWeight" type="number" step="0.05" min="0" max="1" defaultValue={inputPolicy.oddsWeight} />
                    <p className="text-xs text-muted-foreground">
                      Every source (raw Elo, projections, futures odds) becomes an Elo, then they blend into
                      the single Elo that feeds the simulator. This is the weight given to futures odds:
                      <strong> 0</strong> = Elo / projections only, <strong>1</strong> = futures fully override,
                      in between = blend (e.g. 0.3 = 70% Elo / 30% futures). Odds enter the engine only through
                      this Elo — they are not blended again per game.
                    </p>
                  </div>
                  {projectionEloKey && (
                    <div className="space-y-2 md:col-span-5">
                      <Label htmlFor="baseEloPriority">Base Elo Source</Label>
                      <select
                        id="baseEloPriority"
                        name="baseEloPriority"
                        className="h-9 w-full rounded-md border bg-background px-3 text-sm"
                        defaultValue={projectionsOutrankElo ? "projectionsFirst" : "eloFirst"}
                      >
                        <option value="eloFirst">Entered Elo first, then {simulatorInputLabel(projectionEloKey)}</option>
                        <option value="projectionsFirst">{simulatorInputLabel(projectionEloKey)} first, then entered Elo</option>
                      </select>
                      <p className="text-xs text-muted-foreground">
                        Raw Elo and projections are substitutes — the first one a participant has wins, and
                        the other is ignored (futures odds are separate and blend on top via the weight above).
                        Pick <strong>{simulatorInputLabel(projectionEloKey)} first</strong> when projections are
                        the source of truth for this season and a previously entered Elo should not override them.
                      </p>
                    </div>
                  )}
                  {config.profile.requiredInputs.includes("sourceElo") && (
                    <>
                      <div className="space-y-2 md:col-span-2">
                        <Label htmlFor="missingEloStrategy">Missing Elo Strategy</Label>
                        <select
                          id="missingEloStrategy"
                          name="missingEloStrategy"
                          className="h-9 w-full rounded-md border bg-background px-3 text-sm"
                          defaultValue={inputPolicy.missingEloStrategy}
                        >
                          <option value="block">Block until complete</option>
                          <option value="fallbackElo">Use fixed fallback Elo</option>
                          <option value="averageKnown">Use average known Elo</option>
                          <option value="worstKnownMinus">Use worst known Elo minus delta</option>
                        </select>
                      </div>
                      <div className="space-y-2">
                        <Label htmlFor="fallbackElo">Fallback Elo</Label>
                        <Input id="fallbackElo" name="fallbackElo" type="number" defaultValue={inputPolicy.fallbackElo} />
                      </div>
                      <div className="space-y-2">
                        <Label htmlFor="fallbackEloDelta">Worst Elo Delta</Label>
                        <Input id="fallbackEloDelta" name="fallbackEloDelta" type="number" defaultValue={inputPolicy.fallbackEloDelta} />
                      </div>
                      <div className="space-y-2">
                        <Label htmlFor="eloMin">Elo Floor</Label>
                        <Input id="eloMin" name="eloMin" type="number" defaultValue={inputPolicy.eloMin} />
                      </div>
                      <div className="space-y-2">
                        <Label htmlFor="eloMax">Elo Ceiling</Label>
                        <Input id="eloMax" name="eloMax" type="number" defaultValue={inputPolicy.eloMax} />
                      </div>
                    </>
                  )}
                  {config.profile.requiredInputs.includes("rating") && (
                    <>
                      <div className="space-y-2 md:col-span-2">
                        <Label htmlFor="missingRatingStrategy">Missing Rating Strategy</Label>
                        <select
                          id="missingRatingStrategy"
                          name="missingRatingStrategy"
                          className="h-9 w-full rounded-md border bg-background px-3 text-sm"
                          defaultValue={inputPolicy.missingRatingStrategy}
                        >
                          <option value="block">Block until complete</option>
                          <option value="fallbackRating">Use fixed fallback rating</option>
                          <option value="averageKnown">Use average known rating</option>
                          <option value="worstKnownMinus">Use worst known rating minus delta</option>
                        </select>
                      </div>
                      <div className="space-y-2">
                        <Label htmlFor="fallbackRating">Fallback Rating</Label>
                        <Input id="fallbackRating" name="fallbackRating" type="number" step="0.01" defaultValue={inputPolicy.fallbackRating} />
                      </div>
                      <div className="space-y-2">
                        <Label htmlFor="fallbackRatingDelta">Worst Rating Delta</Label>
                        <Input id="fallbackRatingDelta" name="fallbackRatingDelta" type="number" step="0.01" defaultValue={inputPolicy.fallbackRatingDelta} />
                      </div>
                    </>
                  )}
                  <div className="space-y-2">
                    <Label htmlFor="ratingMin">Rating Floor</Label>
                    <Input id="ratingMin" name="ratingMin" type="number" step="0.01" defaultValue={inputPolicy.ratingMin} />
                  </div>
                  <div className="space-y-2">
                    <Label htmlFor="ratingMax">Rating Ceiling</Label>
                    <Input id="ratingMax" name="ratingMax" type="number" step="0.01" defaultValue={inputPolicy.ratingMax} />
                  </div>
                </div>
              </section>
            )}

            <Button type="submit" disabled={isSubmitting}>
              <Save className="mr-2 h-4 w-4" />
              Save Configuration
            </Button>
          </Form>

          <details>
            <summary className="cursor-pointer text-sm font-medium">Advanced: edit raw config JSON</summary>
            <Form method="post" className="space-y-3 mt-3">
              <input type="hidden" name="intent" value="save-config" />
              <Textarea
                name="config"
                rows={10}
                className="font-mono text-sm"
                defaultValue={JSON.stringify(config.config, null, 2)}
              />
              <p className="text-xs text-muted-foreground">
                Power-user escape hatch for keys not shown above. This is the same stored config the fields
                edit; saving here writes the whole object.
              </p>
              <Button type="submit" variant="outline" disabled={isSubmitting}>
                <Save className="mr-2 h-4 w-4" />
                Save Raw JSON
              </Button>
            </Form>
          </details>
        </CardContent>
      </Card>

      <Card>
        <CardHeader>
          <CardTitle>Bulk Simulator Inputs</CardTitle>
          <CardDescription>
            Two ways to paste, then the simulation re-runs automatically on save:
            <strong> CSV</strong> with a header row — supported columns: name, sourceElo, sourceOdds,
            worldRanking, rating, projectedWins, projectedTablePoints, seed, region (values must not
            contain commas); or <strong>futures odds</strong>, one team per line ending in American
            odds (e.g. <code>Kansas City Chiefs +450</code>). Team names are fuzzy-matched to
            participants. A partial paste only updates the columns it includes — other inputs are kept.
          </CardDescription>
        </CardHeader>
        <CardContent className="space-y-4">
          <Form method="post" className="space-y-4">
            <input type="hidden" name="intent" value="save-inputs" />
            <Textarea
              name="bulkInputs"
              rows={8}
              className="font-mono text-sm"
              placeholder={`name,sourceElo,sourceOdds,worldRanking,rating\n${inputRows[0]?.participant.name ?? "Team Name"},1500,+2500,12,28.5\n\n— or paste futures odds only —\n${inputRows[0]?.participant.name ?? "Team Name"} +2500`}
            />
            <Button type="submit" disabled={isSubmitting}>
              <Save className="mr-2 h-4 w-4" />
              Save Inputs
            </Button>
          </Form>

          {externalInputsSection && (
            <div className="rounded-md border border-sky-500/30 bg-sky-500/10 p-3 text-sm flex items-center justify-between gap-4">
              <span>
                This simulator's participant inputs are managed on the{" "}
                <strong>{externalInputsSection.label}</strong> page — the list below is a roster only.
              </span>
              <Button variant="outline" size="sm" asChild>
                <Link to={externalInputsSection.to}>Go to {externalInputsSection.label}</Link>
              </Button>
            </div>
          )}

          <div className="flex flex-wrap items-center gap-3">
            <Input
              type="search"
              placeholder="Search participants…"
              value={search}
              onChange={(event) => {
                setSearch(event.target.value);
                setPage(0);
              }}
              className="max-w-xs"
            />
            {requiredInputs.length > 0 && (
              <label className="flex items-center gap-2 text-sm text-muted-foreground">
                <input
                  type="checkbox"
                  checked={onlyMissing}
                  onChange={(event) => {
                    setOnlyMissing(event.target.checked);
                    setPage(0);
                  }}
                />
                Only show participants missing a required input
              </label>
            )}
          </div>

          <div className="rounded-md border">
            <div
              className="grid gap-2 border-b px-3 py-2 text-xs font-medium text-muted-foreground"
              style={{ gridTemplateColumns: gridTemplate }}
            >
              <div>Participant</div>
              {inputColumns.length > 0 ? (
                inputColumns.map((column) => (
                  <div key={column.key} className="capitalize">
                    {column.label}
                    {column.required && <span className="text-amber-500"> *</span>}
                  </div>
                ))
              ) : (
                <div>—</div>
              )}
            </div>
            {pageRows.length === 0 ? (
              <div className="px-3 py-6 text-center text-sm text-muted-foreground">
                No participants match.
              </div>
            ) : (
              pageRows.map(({ participant, input }) => {
                const incomplete = isRowIncomplete(participant.id, input);
                return (
                  <div
                    key={participant.id}
                    className="grid gap-2 border-b last:border-b-0 px-3 py-2 text-sm"
                    style={{ gridTemplateColumns: gridTemplate }}
                  >
                    <div className="font-medium flex items-center gap-2">
                      {incomplete && <span className="h-2 w-2 shrink-0 rounded-full bg-amber-500" title="Missing a required input" />}
                      {participant.name}
                    </div>
                    {inputColumns.length > 0 ? (
                      inputColumns.map((column) => {
                        if (column.key === "sourceElo") {
                          const resolved = resolvedEloRows[participant.id];
                          const methodLabel = resolved ? resolvedInputMethodLabel(resolved.method) : null;
                          return (
                            <div key={column.key} className="flex items-center gap-1.5">
                              {resolved ? resolved.sourceElo : "—"}
                              {methodLabel && (
                                <Badge variant="outline" className="text-[10px] font-normal">
                                  {methodLabel}
                                </Badge>
                              )}
                            </div>
                          );
                        }
                        if (column.key === "rating") {
                          const resolved = resolvedRatingRows[participant.id];
                          const methodLabel = resolved ? resolvedInputMethodLabel(resolved.method) : null;
                          return (
                            <div key={column.key} className="flex items-center gap-1.5">
                              {resolved ? resolved.rating : "—"}
                              {methodLabel && (
                                <Badge variant="outline" className="text-[10px] font-normal">
                                  {methodLabel}
                                </Badge>
                              )}
                            </div>
                          );
                        }
                        const value = input?.[column.key];
                        return <div key={column.key}>{typeof value === "number" || typeof value === "string" ? value : "—"}</div>;
                      })
                    ) : (
                      <div>—</div>
                    )}
                  </div>
                );
              })
            )}
            <div className="flex items-center justify-between gap-4 px-3 py-2 text-xs text-muted-foreground">
              <span>
                {filteredRows.length === 0
                  ? "0 participants"
                  : `Showing ${pageStart + 1}–${pageStart + pageRows.length} of ${filteredRows.length}${
                      filteredRows.length !== inputRows.length ? ` (${inputRows.length} total)` : ""
                    }`}
              </span>
              {totalPages > 1 && (
                <div className="flex items-center gap-2">
                  <Button
                    type="button"
                    variant="outline"
                    size="sm"
                    disabled={safePage === 0}
                    onClick={() => setPage(safePage - 1)}
                  >
                    Previous
                  </Button>
                  <span>
                    Page {safePage + 1} of {totalPages}
                  </span>
                  <Button
                    type="button"
                    variant="outline"
                    size="sm"
                    disabled={safePage >= totalPages - 1}
                    onClick={() => setPage(safePage + 1)}
                  >
                    Next
                  </Button>
                </div>
              )}
            </div>
          </div>
        </CardContent>
      </Card>
    </div>
  );
}