import { Router } from "express";
import { z } from "zod";
import { db } from "../db/client.js";
import { requireAuth, type AuthedRequest } from "../middleware.js";
import { permissionService } from "../services/permissionService.js";

const SEVEN_DAYS_MS = 7 * 24 * 60 * 60 * 1000;

const ALIGNMENT_MAP: Record<number, string> = {
  1: "Lawful Good",    2: "Neutral Good",    3: "Chaotic Good",
  4: "Lawful Neutral", 5: "True Neutral",    6: "Chaotic Neutral",
  7: "Lawful Evil",    8: "Neutral Evil",    9: "Chaotic Evil",
};

// ─── D&D Beyond fetch + parse ────────────────────────────────────────────────

async function fetchDndBeyondChar(charId: string): Promise<Record<string, unknown>> {
  const url = `https://character-service.dndbeyond.com/character/v5/character/${charId}`;
  const res = await fetch(url, {
    headers: { "User-Agent": "dnd-hub/1.0 (private campaign manager; not for scraping)" },
    signal: AbortSignal.timeout(10_000),
  });
  if (res.status === 404) {
    throw Object.assign(new Error("Character not found — make sure the character is set to Public on D&D Beyond."), { status: 404 });
  }
  if (res.status === 401 || res.status === 403) {
    throw Object.assign(new Error("Character is private. Set it to Public on D&D Beyond, then try again."), { status: 422 });
  }
  if (!res.ok) throw new Error(`D&D Beyond returned ${res.status}`);
  const json = await res.json() as { data?: Record<string, unknown> };
  if (!json.data) throw new Error("Unexpected response format from D&D Beyond");
  return json.data;
}

interface ParsedChar {
  character_name: string;
  race: string;
  class: string;
  level: number;
  alignment: string | null;
  portrait_url: string | null;
  bio: string | null;
  stats_json: string | null;
}

interface CharStats {
  str: number; dex: number; con: number;
  int: number; wis: number; cha: number;
  maxHp: number | null;
  proficiencyBonus: number;
}

function parseCharStats(data: Record<string, unknown>, level: number): string | null {
  try {
    const baseStats = (data.stats as Array<{id: number; value: number | null}> | undefined) ?? [];
    const bonusStats = (data.bonusStats as Array<{id: number; value: number | null}> | undefined) ?? [];
    const overrideStats = (data.overrideStats as Array<{id: number; value: number | null}> | undefined) ?? [];

    function getAbility(id: number): number {
      const ov = overrideStats.find(s => s.id === id)?.value;
      if (ov != null) return ov;
      const base = baseStats.find(s => s.id === id)?.value ?? 10;
      const bonus = bonusStats.find(s => s.id === id)?.value ?? 0;
      return base + bonus;
    }

    const hpInfo = data.hitPointInfo as { override?: number | null; maximumHitPoints?: number } | undefined;
    const maxHp = hpInfo?.override ?? hpInfo?.maximumHitPoints ?? null;
    const proficiencyBonus = Math.ceil(level / 4) + 1;

    const stats: CharStats = {
      str: getAbility(1), dex: getAbility(2), con: getAbility(3),
      int: getAbility(4), wis: getAbility(5), cha: getAbility(6),
      maxHp: typeof maxHp === 'number' ? maxHp : null,
      proficiencyBonus,
    };
    return JSON.stringify(stats);
  } catch {
    return null;
  }
}

function parseDndBeyondChar(data: Record<string, unknown>): ParsedChar {
  const get = <T>(obj: unknown, ...keys: string[]): T | undefined => {
    let cur: unknown = obj;
    for (const k of keys) {
      if (cur == null || typeof cur !== "object") return undefined;
      cur = (cur as Record<string, unknown>)[k];
    }
    return cur as T;
  };

  const name = (data.name as string | undefined) ?? "Unknown";

  const raceObj = data.race as Record<string, unknown> | null | undefined;
  const race = (raceObj?.fullName ?? raceObj?.baseRaceName ?? "Unknown") as string;

  const classes = (data.classes as Array<Record<string, unknown>> | null | undefined) ?? [];
  const classNames = classes.map(c => get<string>(c, "definition", "name") ?? "Unknown");
  const classStr = classNames.length > 0 ? classNames.join("/") : "Unknown";
  const level = Math.max(1, classes.reduce((sum, c) => sum + ((c.level as number) ?? 0), 0));

  const alignmentId = data.alignmentId as number | null | undefined;
  const alignment = alignmentId ? (ALIGNMENT_MAP[alignmentId] ?? null) : null;

  const portrait_url = (get<string>(data, "decorations", "avatarUrl") ?? null) as string | null;

  const traits = data.traits as Record<string, string | null> | null | undefined;
  const traitParts = [
    traits?.personalityTraits,
    traits?.ideals ? `**Ideals:** ${traits.ideals}` : null,
    traits?.bonds  ? `**Bonds:** ${traits.bonds}`   : null,
    traits?.flaws  ? `**Flaws:** ${traits.flaws}`   : null,
  ].filter(Boolean);
  const bio = traitParts.length > 0 ? traitParts.join("\n\n") : null;

  const stats_json = parseCharStats(data, level);

  return { character_name: name, race, class: classStr, level, alignment, portrait_url, bio, stats_json };
}

// ─── Helper ──────────────────────────────────────────────────────────────────

function getCharacter(characterId: number) {
  return db.prepare(
    "SELECT id, user_id, campaign_id, dndbeyond_id, dndbeyond_last_sync FROM characters WHERE id = ?"
  ).get(characterId) as {
    id: number; user_id: number; campaign_id: number;
    dndbeyond_id: string | null; dndbeyond_last_sync: string | null;
  } | undefined;
}

function applyRefresh(characterId: number, fields: ParsedChar) {
  db.prepare(
    `UPDATE characters
     SET character_name = ?, race = ?, class = ?, level = ?,
         alignment = ?, portrait_url = ?, bio = ?, stats_json = ?,
         dndbeyond_last_sync = datetime('now')
     WHERE id = ?`
  ).run(
    fields.character_name, fields.race, fields.class, fields.level,
    fields.alignment, fields.portrait_url, fields.bio, fields.stats_json,
    characterId,
  );
}

// ─── Routes ──────────────────────────────────────────────────────────────────

export const dndBeyondRoutes = Router();

/**
 * POST /characters/dndbeyond/preview
 * Fetch & parse a D&D Beyond character without saving anything.
 */
dndBeyondRoutes.post("/characters/dndbeyond/preview", requireAuth, async (req: AuthedRequest, res) => {
  const parsed = z.object({
    dndbeyondCharId: z.string().trim().regex(/^\d+$/, "Must be a numeric D&D Beyond character ID"),
  }).safeParse(req.body);

  if (!parsed.success) {
    res.status(400).json({ error: parsed.error.flatten() });
    return;
  }

  try {
    const data = await fetchDndBeyondChar(parsed.data.dndbeyondCharId);
    res.json(parseDndBeyondChar(data));
  } catch (err: unknown) {
    const e = err as { message?: string; status?: number };
    res.status(e.status ?? 502).json({ error: e.message ?? "Failed to fetch character" });
  }
});

/**
 * POST /characters/dndbeyond/import
 * After the user confirms the preview, persist to characters table.
 */
dndBeyondRoutes.post("/characters/dndbeyond/import", requireAuth, (req: AuthedRequest, res) => {
  const schema = z.object({
    campaignId:      z.number().int(),
    dndbeyondCharId: z.string().trim().regex(/^\d+$/),
    character_name:  z.string().min(1),
    race:            z.string().min(1),
    class:           z.string().min(1),
    level:           z.number().int().min(1).max(20),
    alignment:       z.string().nullable().optional(),
    portrait_url:    z.string().url().nullable().optional(),
    bio:             z.string().nullable().optional(),
  });

  const parsed = schema.safeParse(req.body);
  if (!parsed.success) {
    res.status(400).json({ error: parsed.error.flatten() });
    return;
  }

  const { campaignId, dndbeyondCharId, ...fields } = parsed.data;

  const campaign = db
    .prepare("SELECT id FROM campaigns WHERE id = ? AND guild_id = ?")
    .get(campaignId, req.auth!.guildId);
  if (!campaign) {
    res.status(404).json({ error: "Campaign not found" });
    return;
  }

  // Prevent duplicate imports of the same DnD Beyond character for this campaign
  const duplicate = db
    .prepare("SELECT id FROM characters WHERE campaign_id = ? AND dndbeyond_id = ?")
    .get(campaignId, dndbeyondCharId);
  if (duplicate) {
    res.status(409).json({ error: "This D&D Beyond character is already imported for this campaign" });
    return;
  }

  const result = db.prepare(
    `INSERT INTO characters
       (campaign_id, user_id, character_name, race, class, level, alignment,
        portrait_url, bio, is_active, dndbeyond_id, dndbeyond_last_sync, stats_json)
     VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, 0, ?, datetime('now'), ?)`
  ).run(
    campaignId, req.auth!.userId,
    fields.character_name, fields.race, fields.class, fields.level,
    fields.alignment ?? null, fields.portrait_url ?? null, fields.bio ?? null,
    dndbeyondCharId, null,
  );

  res.status(201).json({ id: Number(result.lastInsertRowid) });
});

/**
 * POST /characters/:characterId/dndbeyond/refresh
 * Re-fetch from D&D Beyond. Rate-limited to once per 7 days per character.
 * Only the character owner can call this.
 */
dndBeyondRoutes.post("/characters/:characterId/dndbeyond/refresh", requireAuth, async (req: AuthedRequest, res) => {
  const characterId = Number(req.params.characterId);
  const char = getCharacter(characterId);

  if (!char || char.user_id !== req.auth!.userId) {
    res.status(404).json({ error: "Character not found" });
    return;
  }
  if (!char.dndbeyond_id) {
    res.status(400).json({ error: "Character has no D&D Beyond link" });
    return;
  }

  // Rate-limit
  if (char.dndbeyond_last_sync) {
    const msSince = Date.now() - new Date(char.dndbeyond_last_sync).getTime();
    if (msSince < SEVEN_DAYS_MS) {
      const daysLeft = Math.ceil((SEVEN_DAYS_MS - msSince) / (24 * 60 * 60 * 1000));
      res.status(429).json({
        error: `Refresh available in ${daysLeft} day${daysLeft === 1 ? "" : "s"}`,
        daysLeft,
      });
      return;
    }
  }

  try {
    const data = await fetchDndBeyondChar(char.dndbeyond_id);
    const fields = parseDndBeyondChar(data);
    applyRefresh(characterId, fields);
    res.json({ ok: true, character: fields });
  } catch (err: unknown) {
    const e = err as { message?: string; status?: number };
    res.status(e.status ?? 502).json({ error: e.message ?? "Failed to fetch character" });
  }
});

/**
 * POST /characters/:characterId/dndbeyond/admin-refresh
 * Same as refresh but bypasses the 7-day rate limit.
 * Requires dm or admin role and the character must be in this guild.
 */
dndBeyondRoutes.post("/characters/:characterId/dndbeyond/admin-refresh", requireAuth, async (req: AuthedRequest, res) => {
  if (!permissionService.hasRole(req.auth!.guildId, req.auth!.userId, ["dm", "admin"])) {
    res.status(403).json({ error: "Forbidden" });
    return;
  }

  const characterId = Number(req.params.characterId);
  const char = getCharacter(characterId);
  if (!char) {
    res.status(404).json({ error: "Character not found" });
    return;
  }
  if (!char.dndbeyond_id) {
    res.status(400).json({ error: "Character has no D&D Beyond link" });
    return;
  }

  // Verify the character belongs to a campaign in this guild
  const inGuild = db
    .prepare("SELECT id FROM campaigns WHERE id = ? AND guild_id = ?")
    .get(char.campaign_id, req.auth!.guildId);
  if (!inGuild) {
    res.status(404).json({ error: "Character not found" });
    return;
  }

  try {
    const data = await fetchDndBeyondChar(char.dndbeyond_id);
    const fields = parseDndBeyondChar(data);
    applyRefresh(characterId, fields);
    res.json({ ok: true, character: fields });
  } catch (err: unknown) {
    const e = err as { message?: string; status?: number };
    res.status(e.status ?? 502).json({ error: e.message ?? "Failed to fetch character" });
  }
});