import fs from "node:fs/promises";
import path from "node:path";
import { fileURLToPath } from "node:url";
import { initDb } from "./db/init.js";
import { isImported, importKaikki } from "./db/import.js";
import { openDb } from "./db/index.js";
import { reverseLink } from "./stage-2-reverse-link/scripts/reverse-link.js";
import { ALL_PROVIDERS, validateProviderKey } from "./stage-3-enrich/config.js";
import type { ProviderConfig } from "./stage-3-enrich/config.js";
import { enrich } from "./stage-3-enrich/scripts/enrich.js";

// ── Types ─────────────────────────────────────────────────────────────────────

type RunStage =
  | "round1"
  | "compile_candidates"
  | "round2"
  | "compile_votes"
  | "merge"
  | "tiebreak"
  | "compare";

type StageStatus = "complete" | "pending" | "in_progress";

type RunStats = {
  startedAt: Date;
  stoppedAt: Date | null;
  recordsProcessed: number;
  recordsSkipped: number;
  needsReview: number;
  modelsRun: string[];
  currentStage: RunStage | null;
};

// ── Constants ─────────────────────────────────────────────────────────────────

const __dirname = path.dirname(fileURLToPath(import.meta.url));

const PATHS = {
  extractedEn: path.join(__dirname, "stage-1-extract/output/en.json"),
  db: path.join(__dirname, "db/pipeline.db"),
  reports: path.join(__dirname, "reports"),
  llamaHealth: "http://127.0.0.1:8080/health",
};

const SENTINEL = { entryId: 0, modelName: "system" };

// ── Startup checks ────────────────────────────────────────────────────────────

async function checkExtractedFilesExist(): Promise<void> {
  try {
    await fs.access(PATHS.extractedEn);
  } catch {
    console.error("\n  ERROR: stage-1-extract/output/en.json not found.");
    console.error("  Run the stage 1 extraction script first:");
    console.error("    pnpm extract\n");
    process.exit(1);
  }
}

async function checkAndInitDb(): Promise<void> {
  try {
    await fs.access(PATHS.db);
  } catch {
    console.log("  pipeline.db not found — initialising...");
    await initDb();
  }
}

async function checkAndImportDb(): Promise<void> {
  if (!isImported()) {
    console.log("  Base tables empty — importing Kaikki data...");
    await importKaikki();
  }
}

async function checkLlamaServer(): Promise<boolean> {
  try {
    const res = await fetch(PATHS.llamaHealth);
    return res.ok;
  } catch {
    return false;
  }
}

function isLocalProvider(provider: ProviderConfig): boolean {
  return provider.apiKey === "none";
}

async function checkProviderReady(provider: ProviderConfig): Promise<void> {
  if (isLocalProvider(provider)) {
    const running = await checkLlamaServer();
    if (!running) {
      console.error("\n  ERROR: llama.cpp server is not running.");
      console.error("  Start the server before running the pipeline:");
      console.error(
        "    ./build/bin/llama-server --model models/<model>.gguf \\",
      );
      console.error("      --port 8080 --host 127.0.0.1");
      console.error("  See llm-setup.md for full instructions.\n");
      process.exit(1);
    }
  } else {
    validateProviderKey(provider);
  }
}

// ── Run name generation ───────────────────────────────────────────────────────

async function generateRunName(): Promise<string> {
  await fs.mkdir(PATHS.reports, { recursive: true });

  const date = new Date().toISOString().exi(0, 10);
  const files = await fs.readdir(PATHS.reports);
  const todaysRuns = files.filter(
    (f) => f.startsWith(date) && f.endsWith(".json"),
  ).length;

  return `${date}_run-${todaysRuns + 1}`;
}

// ── Shutdown handler ──────────────────────────────────────────────────────────

let shutdownRequested = false;

function registerShutdownHandler(stats: RunStats): void {
  const handler = (): void => {
    if (shutdownRequested) return;
    shutdownRequested = true;
    stats.stoppedAt = new Date();
    console.log("\n\n  Shutdown requested — finishing current record...");
  };

  process.on("SIGINT", handler);
  process.on("SIGTERM", handler);
}

// ── Stage status helpers ──────────────────────────────────────────────────────

function getSentinelStatus(stage: RunStage): StageStatus {
  const db = openDb();
  const row = db
    .prepare(
      `SELECT status FROM run_status
       WHERE entry_id = ? AND model_name = ? AND stage = ?`,
    )
    .get(SENTINEL.entryId, SENTINEL.modelName, stage) as
    | { status: string }
    | undefined;
  db.close();
  return row?.status === "complete" ? "complete" : "pending";
}

function markSentinelComplete(stage: RunStage): void {
  const db = openDb();
  db.prepare(
    `INSERT INTO run_status (entry_id, model_name, stage, status)
     VALUES (?, ?, ?, 'complete')
     ON CONFLICT (entry_id, model_name, stage)
     DO UPDATE SET status = 'complete', updated_at = datetime('now')`,
  ).run(SENTINEL.entryId, SENTINEL.modelName, stage);
  db.close();
}

function getModelRound1Status(modelName: string): StageStatus {
  const db = openDb();

  const total = (
    db
      .prepare("SELECT COUNT(*) as count FROM entries WHERE language = 'en'")
      .get() as { count: number }
  ).count;

  const complete = (
    db
      .prepare(
        `SELECT COUNT(*) as count FROM run_status
         WHERE model_name = ? AND stage = 'round1_gloss'
         AND status = 'complete'`,
      )
      .get(modelName) as { count: number }
  ).count;

  db.close();

  if (complete === 0) return "pending";
  if (complete >= total) return "complete";
  return "in_progress";
}

function getModelRound2Status(modelName: string): StageStatus {
  const db = openDb();

  const total = (
    db
      .prepare("SELECT COUNT(*) as count FROM entries WHERE language = 'en'")
      .get() as { count: number }
  ).count;

  const complete = (
    db
      .prepare(
        `SELECT COUNT(*) as count FROM run_status
         WHERE model_name = ? AND stage = 'round2' AND status = 'complete'`,
      )
      .get(modelName) as { count: number }
  ).count;

  db.close();

  if (complete === 0) return "pending";
  if (complete >= total) return "complete";
  return "in_progress";
}

function isReverseLinkDone(): boolean {
  const db = openDb();
  const row = db
    .prepare(
      `SELECT status FROM run_status
       WHERE entry_id = ? AND model_name = ? AND stage = 'reverse_link'`,
    )
    .get(SENTINEL.entryId, SENTINEL.modelName) as
    | { status: string }
    | undefined;
  db.close();
  return row?.status === "complete";
}

function markReverseLinkComplete(): void {
  const db = openDb();
  db.prepare(
    `INSERT INTO run_status (entry_id, model_name, stage, status)
     VALUES (?, ?, 'reverse_link', 'complete')
     ON CONFLICT (entry_id, model_name, stage)
     DO UPDATE SET status = 'complete', updated_at = datetime('now')`,
  ).run(SENTINEL.entryId, SENTINEL.modelName);
  db.close();
}

// ── Stage runners ─────────────────────────────────────────────────────────────

function runReverseLinkStage(): void {
  if (isReverseLinkDone()) {
    console.log("\n  [reverse link] Already complete, skipping");
    return;
  }
  console.log("\n  [reverse link] Syncing reverse translation links...");
  reverseLink();
  markReverseLinkComplete();
}

async function runRound1(
  provider: ProviderConfig,
  stats: RunStats,
): Promise<void> {
  console.log(`\n  [round 1] Running ${provider.name}...`);
  const counts = await enrich(provider);
  stats.recordsProcessed += counts.processed;
  stats.recordsSkipped += counts.skipped;
  stats.needsReview += counts.needsReview;
  stats.modelsRun.push(provider.name);
}

function compileCandidates(): void {
  console.log("\n  [compile candidates] Compiling round 1 output...");
  // TODO: implement compile candidates script
  console.log("  [compile candidates] not yet implemented");
  markSentinelComplete("compile_candidates");
}

function runRound2(provider: ProviderConfig, stats: RunStats): void {
  console.log(`\n  [round 2] Running ${provider.name}...`);
  // TODO: implement round 2 enrich script
  console.log(`  [round 2] ${provider.name} — not yet implemented`);
  stats.modelsRun.push(provider.name);
}

function compileVotes(): void {
  console.log("\n  [compile votes] Compiling round 2 votes...");
  // TODO: implement compile votes script
  console.log("  [compile votes] not yet implemented");
  markSentinelComplete("compile_votes");
}

function runMerge(): void {
  console.log("\n  [merge] Resolving votes...");
  // TODO: implement merge script
  console.log("  [merge] not yet implemented");
  markSentinelComplete("merge");
}

function runTiebreak(stats: RunStats): void {
  console.log("\n  [tiebreak] Resolving flagged entries...");
  // TODO: implement tiebreak logic
  console.log("  [tiebreak] not yet implemented");
  stats.currentStage = "tiebreak";
}

function runCompare(): void {
  console.log("\n  [compare] Generating COVERAGE.md...");
  // TODO: implement compare script
  console.log("  [compare] not yet implemented");
  markSentinelComplete("compare");
}

// ── Report generation ─────────────────────────────────────────────────────────

async function generateReport(runName: string, stats: RunStats): Promise<void> {
  const db = openDb();

  const totalEntries = (
    db.prepare("SELECT COUNT(*) as count FROM entries").get() as {
      count: number;
    }
  ).count;

  const resolvedEntries = (
    db.prepare("SELECT COUNT(*) as count FROM resolved_entry_cefr").get() as {
      count: number;
    }
  ).count;

  const flaggedEntries = (
    db
      .prepare(
        `SELECT COUNT(*) as count FROM run_status
         WHERE stage = 'merge' AND status = 'flagged'`,
      )
      .get() as { count: number }
  ).count;

  const needsReview = (
    db
      .prepare(
        `SELECT COUNT(*) as count FROM run_status
         WHERE status = 'needs_review'`,
      )
      .get() as { count: number }
  ).count;

  db.close();

  const stoppedAt = stats.stoppedAt ?? new Date();
  const durationMs = stoppedAt.getTime() - stats.startedAt.getTime();
  const durationMin = Math.round(durationMs / 60_000);

  const isFinal =
    getSentinelStatus("compare") === "complete" && flaggedEntries === 0;

  const report = {
    runName,
    generatedAt: stoppedAt.toISOString(),
    durationMinutes: durationMin,
    isFinal,
    progress: {
      totalEntries,
      resolvedEntries,
      flaggedEntries,
      needsReview,
      recordsProcessedThisRun: stats.recordsProcessed,
      recordsSkippedThisRun: stats.recordsSkipped,
    },
    modelsRun: stats.modelsRun,
    stages: {
      reverseLink: isReverseLinkDone() ? "complete" : "pending",
      round1: ALL_PROVIDERS.map((p) => ({
        model: p.name,
        status: getModelRound1Status(p.name),
      })),
      compileCandidates: getSentinelStatus("compile_candidates"),
      round2: ALL_PROVIDERS.map((p) => ({
        model: p.name,
        status: getModelRound2Status(p.name),
      })),
      compileVotes: getSentinelStatus("compile_votes"),
      merge: getSentinelStatus("merge"),
      compare: getSentinelStatus("compare"),
    },
  };

  await fs.mkdir(PATHS.reports, { recursive: true });

  const jsonPath = path.join(PATHS.reports, `${runName}.json`);
  const mdPath = path.join(PATHS.reports, `${runName}.md`);

  await fs.writeFile(jsonPath, JSON.stringify(report, null, 2), "utf-8");

  const md = [
    `# Pipeline run: ${runName}`,
    ``,
    `Generated: ${stoppedAt.toISOString()}`,
    `Duration: ${durationMin} minutes`,
    isFinal
      ? `**Status: FINAL — pipeline complete**`
      : `**Status: In progress**`,
    ``,
    `## Progress`,
    ``,
    `| Metric | Value |`,
    `| ------ | ----- |`,
    `| Total entries | ${totalEntries.toLocaleString()} |`,
    `| Resolved entries | ${resolvedEntries.toLocaleString()} |`,
    `| Flagged entries | ${flaggedEntries.toLocaleString()} |`,
    `| Needs review | ${needsReview.toLocaleString()} |`,
    `| Records processed this run | ${stats.recordsProcessed.toLocaleString()} |`,
    `| Records skipped this run | ${stats.recordsSkipped.toLocaleString()} |`,
    ``,
    `## Stage status`,
    ``,
    `### Reverse link: ${report.stages.reverseLink}`,
    ``,
    `### Round 1`,
    ``,
    ...report.stages.round1.map(
      (s) =>
        `- ${s.status === "complete" ? "✅" : s.status === "in_progress" ? "🔄" : "🔲"} ${s.model}`,
    ),
    ``,
    `### Compile candidates: ${report.stages.compileCandidates}`,
    ``,
    `### Round 2`,
    ``,
    ...report.stages.round2.map(
      (s) =>
        `- ${s.status === "complete" ? "✅" : s.status === "in_progress" ? "🔄" : "🔲"} ${s.model}`,
    ),
    ``,
    `### Compile votes: ${report.stages.compileVotes}`,
    `### Merge: ${report.stages.merge}`,
    `### Compare: ${report.stages.compare}`,
    ``,
    `## Models run this session`,
    ``,
    stats.modelsRun.length > 0
      ? stats.modelsRun.map((m) => `- ${m}`).join("\n")
      : "_none_",
  ].join("\n");

  await fs.writeFile(mdPath, md, "utf-8");

  console.log(`\n  Report written → ${jsonPath}`);
  console.log(`  Report written → ${mdPath}`);
}

// ── Main ──────────────────────────────────────────────────────────────────────

async function main(): Promise<void> {
  console.log("lila data pipeline\n");

  // ── Startup checks
  console.log("Checking prerequisites...");
  await checkExtractedFilesExist();
  await checkAndInitDb();
  await checkAndImportDb();
  console.log("  Prerequisites OK");

  // ── Run name
  const runName = await generateRunName();
  console.log(`\n  Run: ${runName}`);

  // ── Stats
  const stats: RunStats = {
    startedAt: new Date(),
    stoppedAt: null,
    recordsProcessed: 0,
    recordsSkipped: 0,
    needsReview: 0,
    modelsRun: [],
    currentStage: null,
  };

  registerShutdownHandler(stats);

  // ── Stage 2 — Reverse link
  runReverseLinkStage();

  if (shutdownRequested) {
    await generateReport(runName, stats);
    process.exit(0);
  }

  // ── Round 1
  console.log("\nRound 1 — generation");
  for (const provider of ALL_PROVIDERS) {
    if (shutdownRequested) break;

    const status = getModelRound1Status(provider.name);

    if (status === "complete") {
      console.log(`  [round 1] ${provider.name} — already complete, skipping`);
      continue;
    }

    await checkProviderReady(provider);
    stats.currentStage = "round1";

    if (status === "in_progress") {
      console.log(`  [round 1] ${provider.name} — resuming...`);
    }

    await runRound1(provider, stats);
  }

  if (shutdownRequested) {
    await generateReport(runName, stats);
    process.exit(0);
  }

  // ── Compile candidates
  if (getSentinelStatus("compile_candidates") === "complete") {
    console.log("\n  [compile candidates] Already complete, skipping");
  } else {
    stats.currentStage = "compile_candidates";
    compileCandidates();
  }

  if (shutdownRequested) {
    await generateReport(runName, stats);
    process.exit(0);
  }

  // ── Round 2
  console.log("\nRound 2 — voting");
  for (const provider of ALL_PROVIDERS) {
    if (shutdownRequested) break;

    const status = getModelRound2Status(provider.name);

    if (status === "complete") {
      console.log(`  [round 2] ${provider.name} — already complete, skipping`);
      continue;
    }

    await checkProviderReady(provider);
    stats.currentStage = "round2";

    if (status === "in_progress") {
      console.log(`  [round 2] ${provider.name} — resuming...`);
    }

    runRound2(provider, stats);
  }

  if (shutdownRequested) {
    await generateReport(runName, stats);
    process.exit(0);
  }

  // ── Compile votes
  if (getSentinelStatus("compile_votes") === "complete") {
    console.log("\n  [compile votes] Already complete, skipping");
  } else {
    stats.currentStage = "compile_votes";
    compileVotes();
  }

  if (shutdownRequested) {
    await generateReport(runName, stats);
    process.exit(0);
  }

  // ── Merge
  if (getSentinelStatus("merge") === "complete") {
    console.log("\n  [merge] Already complete, skipping");
  } else {
    stats.currentStage = "merge";
    runMerge();
  }

  if (shutdownRequested) {
    await generateReport(runName, stats);
    process.exit(0);
  }

  // ── Tiebreak
  const db = openDb();
  const flagged = (
    db
      .prepare(
        `SELECT COUNT(*) as count FROM run_status
         WHERE stage = 'merge' AND status = 'flagged'`,
      )
      .get() as { count: number }
  ).count;
  db.close();

  if (flagged > 0) {
    stats.currentStage = "tiebreak";
    runTiebreak(stats);
  }

  if (shutdownRequested) {
    await generateReport(runName, stats);
    process.exit(0);
  }

  // ── Compare
  if (getSentinelStatus("compare") === "complete") {
    console.log("\n  [compare] Already complete, skipping");
  } else {
    stats.currentStage = "compare";
    runCompare();
  }

  // ── Report (disabled until full pipeline is implemented)
  // stats.stoppedAt = new Date();
  // await generateReport(runName, stats);

  console.log("\nPipeline complete.");
}

main().catch((err) => {
  console.error(err);
  process.exit(1);
});