interface DiscordEmbed {
  title?: string;
  description?: string;
  color?: number;
  footer?: { text: string };
}

interface DiscordWebhookPayload {
  content?: string;
  embeds?: DiscordEmbed[];
}

export async function sendDiscordWebhook(
  webhookUrl: string,
  payload: DiscordWebhookPayload
): Promise<void> {
  const response = await fetch(webhookUrl, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify(payload),
  });

  if (!response.ok) {
    const text = await response.text().catch(() => "");
    throw new Error(`Discord webhook failed: ${response.status} ${text}`);
  }
}

export interface StandingEntry {
  teamId: string;
  teamName: string;
  totalPoints: number;
  rank: number;
}

export interface ScoredMatch {
  winnerName: string;
  loserName: string;
}

export async function sendStandingsUpdateNotification({
  webhookUrl,
  seasonName,
  standings,
  previousStandings,
  sportName,
  eventName,
  scoredMatches,
}: {
  webhookUrl: string;
  seasonName: string;
  standings: StandingEntry[];
  previousStandings: Map<string, number>;
  sportName?: string;
  eventName?: string;
  scoredMatches?: ScoredMatch[];
}): Promise<void> {
  const RANK_MEDALS = ["🥇", "🥈", "🥉"];

  const sections: string[] = [];

  // Header: "Sport Name — Event Name"
  if (sportName || eventName) {
    const parts = [sportName, eventName].filter(Boolean);
    sections.push(`**${parts.join(" — ")}**`);
  }

  // Scored matches section
  if (scoredMatches && scoredMatches.length > 0) {
    sections.push("**Scored Matches**");
    for (const match of scoredMatches) {
      sections.push(`• **${match.winnerName}** def. ${match.loserName}`);
    }
  }

  // Standings section
  sections.push("**Current Standings**");
  for (const s of standings) {
    const prev = previousStandings.get(s.teamId);
    let delta = "";
    if (prev !== undefined && prev !== s.totalPoints) {
      const diff = Math.round(s.totalPoints - prev);
      const sign = diff > 0 ? "+" : "";
      delta = ` **(${sign}${diff} pts)**`;
    }
    const medal = RANK_MEDALS[s.rank - 1] ?? `${s.rank}.`;
    sections.push(`${medal} ${s.teamName} — ${Math.round(s.totalPoints)} pts${delta}`);
  }

  const MAX_DESCRIPTION = 4096;
  let description = sections.join("\n");
  if (description.length > MAX_DESCRIPTION) {
    description = description.slice(0, MAX_DESCRIPTION - 3) + "...";
  }

  await sendDiscordWebhook(webhookUrl, {
    embeds: [
      {
        title: `📊 Standings Update — ${seasonName}`,
        description,
        color: 0x5865f2, // Discord blurple
        footer: { text: "brackt.com" },
      },
    ],
  });
}