const path = require("path");

const { fetchChapterLinks, isLikelyComicLandSite } = require("./chapters.js");
const { stemForComicLandChapterCbz, chapterUrlToCbz, sanitizeComicDirName } =
  require("./downloadChapterCbz.js");

/**
 * @typedef {object} ParsedCli
 * @property {boolean} [help] - Print usage and exit when true.
 * @property {string|undefined} listingUrl - Series listing URL (required unless help).
 * @property {boolean} listOnly - Only print the chapter menu.
 * @property {boolean} allChapters - Queue every chapter (API already oldest-first).
 * @property {boolean} missingOnly - Queue chapters that need download (SQLite + CBZ on disk).
 * @property {string|undefined} selectSpec - `--select` string (1-based menu indices).
 * @property {string|undefined} numbersSpec - `--numbers` string (chapter numbers from titles).
 * @property {string} outDir - Output directory for `.cbz` files.
 * @property {boolean} noDb - Skip SQLite updates.
 * @property {number|undefined} titleId - Load listing URL from SQLite title id.
 * @property {boolean} outDirExplicit - True when `--out` was passed.
 * @property {boolean} verbose - Print informational progress logs.
 * @property {number} delaySeconds - Pause between chapter downloads (0 = no delay).
 */

/**
 * @param {string[]} argv - `process.argv`.
 * @returns {ParsedCli} Parsed flags and positional URL.
 */
function parseCli(argv) {
  /** @type {ParsedCli} */
  const result = {
    help: false,
    listingUrl: undefined,
    listOnly: false,
    allChapters: false,
    missingOnly: false,
    selectSpec: undefined,
    numbersSpec: undefined,
    outDir: path.join(process.cwd(), "data", "comicland", "comics"),
    noDb: false,
    titleId: undefined,
    outDirExplicit: false,
    verbose: false,
    delaySeconds: 0,
  };

  for (let i = 2; i < argv.length; i += 1) {
    const a = argv[i];
    if (a === "--help" || a === "-h") {
      result.help = true;
    } else if (a === "--list-only" || a === "-l") {
      result.listOnly = true;
    } else if (a === "--all") {
      result.allChapters = true;
    } else if (a === "--missing") {
      result.missingOnly = true;
    } else if (a === "--verbose" || a === "-v") {
      result.verbose = true;
    } else if (a === "--no-db") {
      result.noDb = true;
    } else if (a === "--delay") {
      const next = argv[i + 1];
      if (next === undefined || (next.startsWith("-") && !/^-?\d+$/u.test(next))) {
        throw new Error("Missing value for --delay");
      }
      const seconds = Number.parseInt(next, 10);
      if (!Number.isFinite(seconds) || seconds < 0) {
        throw new Error(`Invalid --delay: ${next} (expected non-negative integer seconds)`);
      }
      result.delaySeconds = seconds;
      i += 1;
    } else if (a === "--title-id") {
      const next = argv[i + 1];
      if (next === undefined || next.startsWith("-")) {
        throw new Error("Missing value for --title-id");
      }
      const id = Number.parseInt(next, 10);
      if (!Number.isFinite(id) || id < 1) {
        throw new Error(`Invalid --title-id: ${next}`);
      }
      result.titleId = id;
      i += 1;
    } else if (a === "--select" || a === "-s") {
      const next = argv[i + 1];
      if (next === undefined || next.startsWith("-")) {
        throw new Error("Missing value for --select");
      }
      result.selectSpec = next;
      i += 1;
    } else if (a === "--numbers" || a === "-n") {
      const next = argv[i + 1];
      if (next === undefined || next.startsWith("-")) {
        throw new Error("Missing value for --numbers");
      }
      result.numbersSpec = next;
      i += 1;
    } else if (a === "--out" || a === "-o") {
      const next = argv[i + 1];
      if (next === undefined || next.startsWith("-")) {
        throw new Error("Missing value for --out");
      }
      result.outDir = path.resolve(next);
      result.outDirExplicit = true;
      i += 1;
    } else if (!a.startsWith("-")) {
      if (result.listingUrl) {
        throw new Error(`Unexpected extra argument: ${a}`);
      }
      result.listingUrl = a;
    } else {
      throw new Error(`Unknown option: ${a}`);
    }
  }

  return result;
}

/**
 * @param {boolean} verbose - When false, no-op.
 * @returns {(msg: string) => void} Logger.
 */
function makeVlog(verbose) {
  return (msg) => {
    if (verbose) {
      console.log(`info: ${msg}`);
    }
  };
}

/**
 * @param {number} seconds - Seconds to wait.
 * @returns {Promise<void>}
 */
function sleepSeconds(seconds) {
  return new Promise((resolve) => {
    setTimeout(resolve, seconds * 1000);
  });
}

/**
 * Build a download queue from SQLite chapters that still need a CBZ.
 * @param {import("./chapters.js").ChapterLink[]} chapters - Oldest-first listing.
 * @param {object[]} needingRows - Chapter rows from SQLite.
 * @returns {Array<{ url: string, title: string, pickLabel: string }>} Queue items.
 */
function queueItemsMissing(chapters, needingRows) {
  /** @type {Map<string, object>} */
  const byUrl = new Map();
  for (const row of needingRows) {
    if (typeof row.url === "string" && row.url) {
      byUrl.set(row.url, row);
    }
  }

  /** @type {Array<{ url: string, title: string, pickLabel: string }>} */
  const items = [];
  /** @type {Set<string>} */
  const used = new Set();

  for (const ch of chapters) {
    const row = byUrl.get(ch.url);
    if (!row) {
      continue;
    }
    used.add(ch.url);
    const reason =
      row.status === "downloaded" ? "file-missing" : String(row.status);
    items.push({
      url: ch.url,
      title: ch.title,
      pickLabel: `missing:${reason}`,
    });
  }

  for (const row of needingRows) {
    if (typeof row.url !== "string" || !row.url || used.has(row.url)) {
      continue;
    }
    const reason =
      row.status === "downloaded" ? "file-missing" : String(row.status);
    items.push({
      url: row.url,
      title: row.label || row.chapter_key || row.url,
      pickLabel: `missing:${reason}`,
    });
  }

  return items;
}

/**
 * Chapters that need a download (status pending/failed, or downloaded CBZ gone).
 * @param {import("better-sqlite3").Database} db - Database handle.
 * @param {number} titleId - Title id.
 * @param {(path: string|null|undefined) => boolean} cbzExistsFn - File check.
 * @returns {object[]} Chapter rows.
 */
function listChaptersMissing(db, titleId, cbzExistsFn) {
  const dbApi = require("../server/db.js");
  const rows = dbApi.listChapters(db, titleId);
  return rows.filter((ch) => {
    if (ch.status === "pending" || ch.status === "failed") {
      return true;
    }
    if (ch.status === "downloaded" && !cbzExistsFn(ch.cbz_path)) {
      return true;
    }
    return false;
  });
}

/**
 * ComicLand API already returns oldest-first; copy so callers can mutate safely.
 * @param {import("./chapters.js").ChapterLink[]} chapters - Site/API order.
 * @returns {import("./chapters.js").ChapterLink[]} New array, oldest chapter first.
 */
function chaptersInReadingOrder(chapters) {
  return [...chapters];
}

/**
 * @param {string} spec - `--select` value.
 * @param {number} count - Chapter count.
 * @returns {number[]} Sorted unique 1-based row indices.
 */
function parseChapterSelection(spec, count) {
  if (count <= 0) {
    throw new Error("Chapter list is empty; cannot select indices.");
  }

  const trimmed = spec.trim();
  if (trimmed.length === 0) {
    throw new Error("--select value is empty.");
  }

  /** @type {Set<number>} */
  const seen = new Set();

  for (const rawPart of trimmed.split(",")) {
    const part = rawPart.trim();
    if (part.length === 0) {
      continue;
    }

    if (/^\d+$/u.test(part)) {
      const n = Number.parseInt(part, 10);
      if (n < 1 || n > count) {
        throw new Error(
          `Index ${String(n)} is out of range (valid: 1–${String(count)}).`,
        );
      }
      seen.add(n);
      continue;
    }

    const rangeMatch = /^(\d+)\s*-\s*(\d+)$/u.exec(part);
    if (rangeMatch) {
      const lo = Number.parseInt(rangeMatch[1], 10);
      const hi = Number.parseInt(rangeMatch[2], 10);
      const a = Math.min(lo, hi);
      const b = Math.max(lo, hi);
      for (let j = a; j <= b; j += 1) {
        if (j < 1 || j > count) {
          throw new Error(
            `Range ${part} includes invalid index ${String(j)} (valid: 1–${String(count)}).`,
          );
        }
        seen.add(j);
      }
      continue;
    }

    throw new Error(`Invalid --select segment: "${part}"`);
  }

  if (seen.size === 0) {
    throw new Error("No indices parsed from --select.");
  }

  return [...seen].sort((x, y) => x - y);
}

/**
 * @param {string} title - e.g. `Chapter 22`.
 * @returns {string|null} Chapter number string from title, or null.
 */
function chapterNumberFromListingTitle(title) {
  const m = /^Chapter\s+([\d.]+)\s*$/iu.exec(title.trim().replace(/\s+/gu, " "));
  return m ? m[1] : null;
}

/**
 * @param {string} spec - `--numbers` argument.
 * @returns {string[]} Ordered unique chapter number strings as entered.
 */
function parseChapterNumbersSpec(spec) {
  const trimmed = spec.trim();
  if (trimmed.length === 0) {
    throw new Error("--numbers value is empty.");
  }

  /** @type {string[]} */
  const ordered = [];
  /** @type {Set<string>} */
  const seen = new Set();

  for (const rawPart of trimmed.split(",")) {
    const part = rawPart.trim();
    if (part.length === 0) {
      continue;
    }

    const rangeMatch = /^(\d+)\s*-\s*(\d+)$/u.exec(part);
    if (rangeMatch) {
      const lo = Number.parseInt(rangeMatch[1], 10);
      const hi = Number.parseInt(rangeMatch[2], 10);
      const a = Math.min(lo, hi);
      const b = Math.max(lo, hi);
      for (let n = a; n <= b; n += 1) {
        const k = String(n);
        if (!seen.has(k)) {
          seen.add(k);
          ordered.push(k);
        }
      }
      continue;
    }

    if (/^\d+(\.\d+)?$/u.test(part)) {
      if (!seen.has(part)) {
        seen.add(part);
        ordered.push(part);
      }
      continue;
    }

    throw new Error(`Invalid --numbers segment: "${part}"`);
  }

  if (ordered.length === 0) {
    throw new Error("No chapter numbers parsed from --numbers.");
  }

  return ordered;
}

/**
 * @param {string[]} orderedNums - Chapter numbers requested.
 * @param {import("./chapters.js").ChapterLink[]} chapters - Oldest→newest.
 * @returns {Array<{ url: string, title: string, pickLabel: string }>} Rows to download.
 */
function queueItemsByChapterNumbers(orderedNums, chapters) {
  /** @type {Map<string, import("./chapters.js").ChapterLink>} */
  const first = new Map();
  for (const ch of chapters) {
    const num = chapterNumberFromListingTitle(ch.title);
    if (num !== null && !first.has(num)) {
      first.set(num, ch);
    }
  }

  return orderedNums.map((num) => {
    const ch = first.get(num);
    if (!ch) {
      throw new Error(
        `No chapter titled "Chapter ${num}" in the ComicLand listing. ` +
          "Use --list-only and check titles.",
      );
    }
    return {
      url: ch.url,
      title: ch.title,
      pickLabel: `Ch.${num}`,
    };
  });
}

/**
 * @param {import("./chapters.js").ChapterLink[]} chapters - Oldest-first list.
 * @returns {void}
 */
function printChapterMenu(chapters) {
  const digits = String(chapters.length).length;
  for (let i = 0; i < chapters.length; i += 1) {
    const n = i + 1;
    const pad = String(n).padStart(digits, " ");
    const title = chapters[i].title.replace(/\s+/gu, " ").trim();
    console.log(`${pad}. ${title}`);
    console.log(`     ${chapters[i].url}`);
  }
}

/**
 * @param {number[]} indices1 - Sorted 1-based indices.
 * @param {import("./chapters.js").ChapterLink[]} chapters - Oldest-first chapter list.
 * @returns {Array<{ url: string, title: string, pickLabel: string }>} Queue rows.
 */
function chaptersByIndices(indices1, chapters) {
  return indices1.map((idx) => ({
    url: chapters[idx - 1].url,
    title: chapters[idx - 1].title,
    pickLabel: `#${String(idx)}`,
  }));
}

/**
 * CLI entry: fetch listing, optionally build `.cbz` archives.
 * Upserts titles/chapters into SQLite unless `--no-db`.
 * @returns {Promise<void>}
 */
async function main() {
  let parsed;
  try {
    parsed = parseCli(process.argv);
  } catch (err) {
    console.error(err instanceof Error ? err.message : err);
    process.exitCode = 1;
    return;
  }

  if (parsed.help) {
    console.log(`ComicLand chapter queue (JSON API; URLs like /comic/{slug}):

Usage:
  node src/comicland/downloadChaptersQueue.js <listing-url> [--list-only|-l]
  node src/comicland/downloadChaptersQueue.js <listing-url> --numbers|-n <spec> [--out|-o <dir>]
  node src/comicland/downloadChaptersQueue.js <listing-url> --select|-s <spec> [--out|-o <dir>]
  node src/comicland/downloadChaptersQueue.js <listing-url> --all [--out|-o <dir>]
  node src/comicland/downloadChaptersQueue.js <listing-url> --missing [--out|-o <dir>]
  node src/comicland/downloadChaptersQueue.js --title-id <id> --missing …
  node src/comicland/downloadChaptersQueue.js --title-id <id> --numbers|-n <spec> …

Listing URL: series page https://comicland.org/comic/{slug} (chapter URL is also accepted).

--title-id: load listing URL from SQLite (DATA_DIR/app.db) instead of a URL argument
--missing:  download chapters that are pending, failed, or downloaded but CBZ missing (requires SQLite)
--delay N:  wait N seconds between chapter downloads (e.g. --delay 300)
--no-db:    write CBZ files only; do not update SQLite (incompatible with --missing / --title-id)
--verbose|-v: print informational progress logs
DATA_DIR:   data root (default: ./data)

Default --out: data/comicland/comics/<comic title>/
  (with DB and no --out: $DATA_DIR/comicland/comics/<comic title>/)

--numbers: titles like "Chapter 22", e.g. 22,23,24 or 22-24
--select: 1-based rows on printed list (line 1 = Chapter 1)
`);
    return;
  }

  const vlog = makeVlog(parsed.verbose);
  const cliStore = require("../server/cli-store.js");
  const { resolveCbzPath, cbzExists } = require("../server/sources.js");
  const dbApi = require("../server/db.js");

  /** @type {import("better-sqlite3").Database|null} */
  let db = null;
  /** @type {string|undefined} */
  let dataDir;
  /** @type {object|undefined} */
  let dbTitle;

  try {
    if (parsed.missingOnly && parsed.noDb) {
      console.error("Cannot combine --missing with --no-db (SQLite is required).");
      process.exitCode = 1;
      return;
    }

    if (!parsed.noDb || parsed.titleId !== undefined || parsed.missingOnly) {
      if (parsed.noDb && parsed.titleId !== undefined) {
        console.error("Cannot combine --no-db with --title-id.");
        process.exitCode = 1;
        return;
      }
      vlog(`opening SQLite under DATA_DIR=${cliStore.resolveDataDir()}`);
      ({ db, dataDir } = cliStore.openCliDatabase());
      vlog(`database ready: ${path.join(dataDir, "app.db")}`);
    }

    if (parsed.titleId !== undefined) {
      vlog(`looking up --title-id ${String(parsed.titleId)}`);
      dbTitle = dbApi.getTitle(/** @type {import("better-sqlite3").Database} */ (db), parsed.titleId);
      if (!dbTitle) {
        console.error(`Title id ${String(parsed.titleId)} not found in SQLite.`);
        process.exitCode = 1;
        return;
      }
      if (dbTitle.source !== "comicland") {
        console.error(
          `Title id ${String(parsed.titleId)} is source "${dbTitle.source}"; use the matching CLI.`,
        );
        process.exitCode = 1;
        return;
      }
      parsed.listingUrl = dbTitle.url;
      vlog(`resolved title "${dbTitle.title}" → ${dbTitle.url}`);
    }

    if (!parsed.listingUrl) {
      console.error(
        "Usage: node src/comicland/downloadChaptersQueue.js <listing-url> [options]\n" +
          "Or: --title-id <id> [options]",
      );
      process.exitCode = 1;
      return;
    }

    if (!isLikelyComicLandSite(parsed.listingUrl)) {
      console.warn(
        "Warning: URL hostname does not look like ComicLand; the API client may fail.",
      );
    }

    vlog(`fetching chapter listing: ${parsed.listingUrl}`);
    let chapters;
    let comicTitle;
    try {
      ({ chapters, comicTitle } = await fetchChapterLinks(parsed.listingUrl));
      chapters = chaptersInReadingOrder(chapters);
    } catch (err) {
      console.error(err instanceof Error ? err.message : err);
      process.exitCode = 1;
      return;
    }

    console.log(`Found ${String(chapters.length)} ComicLand chapter link(s).`);
    printChapterMenu(chapters);
    vlog(`comic title from listing: ${comicTitle}`);

    if (parsed.listOnly) {
      if (db && dataDir) {
        vlog("upserting title/chapters into SQLite (--list-only)");
        const result = await cliStore.ensureTitleFromUrl(db, parsed.listingUrl, dataDir);
        console.log(
          `\nSQLite: title id=${String(result.title.id)} "${result.title.title}" ` +
            `(${result.created ? "created" : "updated"}), ` +
            `+${String(result.added)} chapter(s), total ${String(result.total)}`,
        );
      }
      return;
    }

    const wantsAll = parsed.allChapters;
    const wantsMissing = parsed.missingOnly;
    const wantsSelect = Boolean(parsed.selectSpec);
    const wantsNumbers = Boolean(parsed.numbersSpec);
    const pickModes = [wantsAll, wantsMissing, wantsSelect, wantsNumbers].filter(
      Boolean,
    ).length;
    if (pickModes === 0) {
      console.error("Choose --numbers, --select, --all, or --missing (or --list-only).");
      process.exitCode = 1;
      return;
    }
    if (pickModes > 1) {
      console.error("Use only one of --all, --missing, --select, or --numbers.");
      process.exitCode = 1;
      return;
    }

    if (db && dataDir) {
      vlog("upserting title/chapters into SQLite");
      const result = await cliStore.ensureTitleFromUrl(db, parsed.listingUrl, dataDir);
      dbTitle = result.title;
      console.log(
        `SQLite: title id=${String(dbTitle.id)} "${dbTitle.title}" ` +
          `(${result.created ? "created" : "updated"}), ` +
          `+${String(result.added)} chapter(s), total ${String(result.total)}`,
      );
    }

    /** @type {Array<{ url: string, title: string, pickLabel: string }>} */
    let queue;
    try {
      if (wantsMissing) {
        if (!db || !dbTitle) {
          console.error("--missing requires SQLite (omit --no-db).");
          process.exitCode = 1;
          return;
        }
        vlog("selecting chapters that need download (pending/failed/missing CBZ)");
        const needing = listChaptersMissing(db, dbTitle.id, cbzExists);
        queue = queueItemsMissing(chapters, needing);
        console.log(
          `Missing: ${String(queue.length)} chapter(s) need download ` +
            `(of ${String(chapters.length)} on listing).`,
        );
        if (queue.length === 0) {
          console.log("Nothing to download.");
          return;
        }
      } else if (wantsAll) {
        vlog(`queue mode: --all (${String(chapters.length)} chapter(s))`);
        const indices = Array.from({ length: chapters.length }, (_, i) => i + 1);
        queue = chaptersByIndices(indices, chapters);
      } else if (wantsSelect) {
        vlog(`queue mode: --select ${parsed.selectSpec}`);
        const indices = parseChapterSelection(
          /** @type {string} */ (parsed.selectSpec),
          chapters.length,
        );
        queue = chaptersByIndices(indices, chapters);
      } else {
        vlog(`queue mode: --numbers ${parsed.numbersSpec}`);
        const orderedNums = parseChapterNumbersSpec(
          /** @type {string} */ (parsed.numbersSpec),
        );
        queue = queueItemsByChapterNumbers(orderedNums, chapters);
      }
    } catch (err) {
      console.error(err instanceof Error ? err.message : err);
      process.exitCode = 1;
      return;
    }

    vlog(`download queue size: ${String(queue.length)}`);

    const titleForPaths = (dbTitle && dbTitle.title) || comicTitle;
    const useDbPaths = Boolean(db && dataDir && dbTitle && !parsed.outDirExplicit);
    const fallbackOutDir = path.join(parsed.outDir, sanitizeComicDirName(comicTitle));
    const outDir =
      useDbPaths && queue.length > 0
        ? path.dirname(
            resolveCbzPath(
              "comicland",
              titleForPaths,
              queue[0].url,
              /** @type {string} */ (dataDir),
            ),
          )
        : fallbackOutDir;
    console.log(`Comic: ${comicTitle}`);
    console.log(`Output directory: ${outDir}`);
    if (parsed.delaySeconds > 0) {
      console.log(`Delay between chapters: ${String(parsed.delaySeconds)}s`);
    }

    let failedCount = 0;
    let done = 0;
    for (const item of queue) {
      done += 1;
      const stem = stemForComicLandChapterCbz(item.url);
      let targetPath = path.join(fallbackOutDir, `${stem}.cbz`);
      /** @type {object|undefined} */
      let chapterRow;

      if (useDbPaths) {
        targetPath = resolveCbzPath(
          "comicland",
          titleForPaths,
          item.url,
          /** @type {string} */ (dataDir),
        );
        chapterRow = cliStore.findChapterByUrl(
          /** @type {import("better-sqlite3").Database} */ (db),
          dbTitle.id,
          item.url,
        );
      } else if (db && dbTitle) {
        chapterRow = cliStore.findChapterByUrl(db, dbTitle.id, item.url);
      }

      console.log(`\n[${String(done)}/${String(queue.length)}] ${item.pickLabel} ${item.title}`);
      console.log(`  → ${item.url}`);
      vlog(`target CBZ: ${targetPath}`);

      try {
        if (db && chapterRow) {
          cliStore.markDownload(db, chapterRow, { ok: true, phase: "start" });
        }
        const { imageCount, outputPath } = await chapterUrlToCbz(item.url, targetPath);
        console.log(`  ✓ ${String(imageCount)} page(s) → ${outputPath}`);
        if (db && chapterRow) {
          cliStore.markDownload(db, chapterRow, {
            ok: true,
            cbzPath: outputPath,
            phase: "finish",
          });
        }
      } catch (err) {
        const msg = err instanceof Error ? err.message : String(err);
        console.error(`  ✗ ${msg}`);
        if (db && chapterRow) {
          cliStore.markDownload(db, chapterRow, {
            ok: false,
            error: msg,
            phase: "finish",
          });
        }
        failedCount += 1;
      }

      if (parsed.delaySeconds > 0 && done < queue.length) {
        console.log(
          `  … waiting ${String(parsed.delaySeconds)}s before next chapter`,
        );
        await sleepSeconds(parsed.delaySeconds);
      }
    }

    if (failedCount > 0) {
      console.error(
        `\n${String(failedCount)} chapter(s) failed (${String(queue.length - failedCount)} succeeded).`,
      );
      process.exitCode = 1;
    }
  } finally {
    if (db) {
      db.close();
    }
  }
}

module.exports = {
  chapterNumberFromListingTitle,
  chaptersByIndices,
  chaptersInReadingOrder,
  listChaptersMissing,
  parseChapterNumbersSpec,
  parseChapterSelection,
  parseCli,
  printChapterMenu,
  queueItemsByChapterNumbers,
  queueItemsMissing,
};

if (require.main === module) {
  main().catch((err) => {
    console.error(err);
    process.exitCode = 1;
  });
}