import { appendFileSync, mkdirSync, writeFileSync } from "node:fs";
import path from "node:path";
import { parseArgs } from "node:util";
import {
  SUPPORTED_LANGUAGE_CODES,
  SUPPORTED_POS,
  type SupportedLanguageCode,
  type SupportedPos,
} from "@lila/shared";
import {
  DEFAULT_MODEL,
  buildEntriesResponseSchema,
  generateContent,
  parseEntries,
} from "./gemini.js";
import { loadPromptTemplate, renderPrompt } from "./promptTemplate.js";
import { discoverSourceLists, type SourceList } from "./sourceLists.js";
import {
  countStagedRows,
  getStagedHeadwords,
  openStaging,
  stageEntry,
} from "./staging.js";
import { validateEntry, type ValidationContext } from "./validate.js";

const ROOT = import.meta.dirname;
const SOURCE_DATA_DIR = path.join(ROOT, "source-data");
const STAGING_DB_PATH = path.join(ROOT, "db", "staging.db");
const STAGING_SCHEMA_PATH = path.join(ROOT, "db", "schema.sql");
const RESPONSES_DIR = path.join(ROOT, "responses");
const REJECTIONS_DIR = path.join(ROOT, "rejections");

type CliOptions = {
  langs: SupportedLanguageCode[] | null;
  pos: SupportedPos;
  maxBatches: number | null;
  batchSize: number;
  delayMs: number;
  dryRun: boolean;
};

type ListStats = {
  list: SourceList;
  pending: number;
  batchesRun: number;
  staged: number;
  skipped: number;
  rejected: number;
  normalized: number;
  failedBatches: number;
};

const parseCli = (): CliOptions => {
  // pnpm forwards the "--" separator itself (pnpm pipeline:run -- --langs …);
  // drop it so the flags after it are parsed as flags, not positionals.
  const args = process.argv.slice(2);
  if (args[0] === "--") args.shift();
  const { values } = parseArgs({
    args,
    options: {
      langs: { type: "string" },
      pos: { type: "string", default: "noun" },
      "max-batches": { type: "string" },
      "batch-size": { type: "string", default: "20" },
      "delay-ms": { type: "string", default: "6000" },
      "dry-run": { type: "boolean", default: false },
    },
  });

  const pos = values.pos as SupportedPos;
  if (!(SUPPORTED_POS as readonly string[]).includes(pos)) {
    throw new Error(`--pos must be one of ${SUPPORTED_POS.join(", ")}`);
  }
  let langs: SupportedLanguageCode[] | null = null;
  if (values.langs !== undefined) {
    langs = values.langs.split(",").map((code) => {
      const trimmed = code.trim() as SupportedLanguageCode;
      if (!(SUPPORTED_LANGUAGE_CODES as readonly string[]).includes(trimmed)) {
        throw new Error(`--langs: unknown language code "${trimmed}"`);
      }
      return trimmed;
    });
  }
  return {
    langs,
    pos,
    maxBatches:
      values["max-batches"] !== undefined
        ? Number(values["max-batches"])
        : null,
    batchSize: Number(values["batch-size"]),
    delayMs: Number(values["delay-ms"]),
    dryRun: values["dry-run"],
  };
};

const chunk = <T>(items: readonly T[], size: number): T[][] => {
  const chunks: T[][] = [];
  for (let i = 0; i < items.length; i += size) {
    chunks.push(items.slice(i, i + size));
  }
  return chunks;
};

const sleep = (ms: number): Promise<void> =>
  new Promise((resolve) => setTimeout(resolve, ms));

const rejectionFile = (list: SourceList): string =>
  path.join(REJECTIONS_DIR, `${list.sourceLanguage}-${list.pos}.jsonl`);

const logRejection = (
  list: SourceList,
  headword: string | null,
  errors: string[],
  entry: unknown,
): void => {
  mkdirSync(REJECTIONS_DIR, { recursive: true });
  const line = JSON.stringify({
    at: new Date().toISOString(),
    sourceLanguage: list.sourceLanguage,
    pos: list.pos,
    headword,
    errors,
    entry,
  });
  appendFileSync(rejectionFile(list), `${line}\n`);
};

const saveRawResponse = (
  list: SourceList,
  batchIndex: number,
  model: string,
  words: readonly string[],
  targetLanguages: readonly SupportedLanguageCode[],
  rawText: string,
): void => {
  mkdirSync(RESPONSES_DIR, { recursive: true });
  const stamp = new Date().toISOString().replaceAll(":", "-");
  const file = path.join(
    RESPONSES_DIR,
    `${list.sourceLanguage}-${list.pos}-${stamp}-batch${batchIndex}.json`,
  );
  writeFileSync(
    file,
    JSON.stringify(
      {
        model,
        sourceLanguage: list.sourceLanguage,
        pos: list.pos,
        targetLanguages,
        words,
        receivedAt: new Date().toISOString(),
        rawText,
      },
      null,
      2,
    ),
  );
};

const headwordOf = (entry: unknown): string | null => {
  if (typeof entry === "object" && entry !== null && !Array.isArray(entry)) {
    const headword = (entry as Record<string, unknown>)["headword"];
    if (typeof headword === "string") return headword;
  }
  return null;
};

const main = async (): Promise<void> => {
  const options = parseCli();
  const model = process.env["GEMINI_MODEL"] ?? DEFAULT_MODEL;
  const apiKey = process.env["GEMINI_API_KEY"];
  if (apiKey === undefined && !options.dryRun) {
    throw new Error("GEMINI_API_KEY is not set (data-pipeline/.env)");
  }

  const allLists = discoverSourceLists(SOURCE_DATA_DIR);
  console.log(`found ${allLists.length} source lists:\n`);
  for (const list of allLists) {
    console.log(
      `  ${list.sourceLanguage}: ${list.pos} (${list.words.length} unique words)`,
    );
  }

  const lists = allLists.filter(
    (list) =>
      list.pos === options.pos &&
      (options.langs === null || options.langs.includes(list.sourceLanguage)),
  );
  if (lists.length === 0) {
    console.log("\nnothing matches the requested --langs/--pos, exiting");
    return;
  }

  const template = loadPromptTemplate();
  const db = openStaging(STAGING_DB_PATH, STAGING_SCHEMA_PATH);
  const allStats: ListStats[] = [];
  let firstApiCall = true;

  for (const list of lists) {
    const staged = getStagedHeadwords(db, list.sourceLanguage, list.pos);
    const pending = list.words.filter((word) => !staged.has(word));
    const targetLanguages = SUPPORTED_LANGUAGE_CODES.filter(
      (code) => code !== list.sourceLanguage,
    );
    const batches = chunk(pending, options.batchSize).slice(
      0,
      options.maxBatches ?? Number.POSITIVE_INFINITY,
    );

    console.log(
      `\n${list.sourceLanguage}/${list.pos}: ${list.words.length} unique, ${staged.size} already staged, ${pending.length} pending → running ${batches.length} batch(es)`,
    );
    const stats: ListStats = {
      list,
      pending: pending.length,
      batchesRun: 0,
      staged: 0,
      skipped: 0,
      rejected: 0,
      normalized: 0,
      failedBatches: 0,
    };
    allStats.push(stats);

    for (const [batchIndex, words] of batches.entries()) {
      const prompt = renderPrompt(template, {
        sourceLanguage: list.sourceLanguage,
        pos: list.pos,
        targetLanguages,
        words,
      });

      if (options.dryRun) {
        console.log(
          `  [dry-run] batch ${batchIndex + 1}/${batches.length}: ${words.join(", ")}`,
        );
        stats.batchesRun++;
        continue;
      }

      if (!firstApiCall) {
        await sleep(options.delayMs);
      }
      firstApiCall = false;

      try {
        const rawText = await generateContent(
          apiKey as string,
          model,
          prompt,
          buildEntriesResponseSchema(
            list.sourceLanguage,
            list.pos,
            targetLanguages,
          ),
        );
        saveRawResponse(
          list,
          batchIndex + 1,
          model,
          words,
          targetLanguages,
          rawText,
        );

        const entries = parseEntries(rawText);
        const ctx: ValidationContext = {
          sourceLanguage: list.sourceLanguage,
          pos: list.pos,
          targetLanguages,
          inputWords: new Set(words),
        };
        const covered = new Set<string>();
        for (const entry of entries) {
          const result = validateEntry(entry, ctx);
          if (result.status === "valid") {
            stageEntry(db, result.entry);
            covered.add(result.entry.headword);
            stats.staged++;
            if (result.normalizations.length > 0) {
              stats.normalized++;
              for (const note of result.normalizations) {
                console.log(`  normalized "${result.entry.headword}" ${note}`);
              }
            }
          } else if (result.status === "empty") {
            covered.add(result.headword);
            stats.skipped++;
            console.log(
              `  skipped "${result.headword}" (no valid ${list.pos} senses)`,
            );
          } else {
            const headword = headwordOf(entry);
            if (headword !== null) covered.add(headword);
            logRejection(list, headword, result.errors, entry);
            stats.rejected++;
          }
        }
        for (const word of words) {
          if (!covered.has(word)) {
            logRejection(list, word, ["missing from Gemini response"], null);
            stats.rejected++;
          }
        }
        stats.batchesRun++;
        console.log(
          `  batch ${batchIndex + 1}/${batches.length} done — ${stats.staged} staged, ${stats.rejected} rejected, ${stats.skipped} skipped`,
        );
      } catch (error) {
        stats.failedBatches++;
        console.error(
          `  batch ${batchIndex + 1}/${batches.length} FAILED: ${error instanceof Error ? error.message : String(error)}`,
        );
      }
    }
  }

  console.log("\n— summary —");
  for (const stats of allStats) {
    console.log(
      `${stats.list.sourceLanguage}/${stats.list.pos}: ${stats.staged} staged (${stats.normalized} normalized), ${stats.skipped} skipped, ${stats.rejected} rejected, ${stats.failedBatches} failed batch(es), ${stats.pending - stats.staged - stats.skipped - stats.rejected} still pending`,
    );
  }
  const totals = countStagedRows(db);
  console.log(
    `staging.db totals: ${totals.words} words, ${totals.senses} senses, ${totals.translations} translations`,
  );
  db.close();
};

main().catch((error: unknown) => {
  console.error(error instanceof Error ? error.message : error);
  process.exitCode = 1;
});