import { mkdirSync, readFileSync } from 'node:fs';
import { dirname, join } from 'node:path';
import { Database } from 'bun:sqlite';
import { drizzle } from 'drizzle-orm/bun-sqlite';
import { load as loadSqliteVec } from 'sqlite-vec';
import { schema } from './schema';

type AppDrizzleDb = ReturnType<typeof createDb>;

declare global {
  // eslint-disable-next-line no-var
  var __fiscalSqliteClient: Database | undefined;
  // eslint-disable-next-line no-var
  var __fiscalDrizzleDb: AppDrizzleDb | undefined;
}

function getDatabasePath() {
  const raw = process.env.DATABASE_URL?.trim() || 'file:data/fiscal.sqlite';
  let databasePath = raw.startsWith('file:') ? raw.slice(5) : raw;

  if (databasePath.startsWith('///')) {
    databasePath = databasePath.slice(2);
  }

  if (!databasePath) {
    throw new Error('DATABASE_URL must point to a SQLite file path.');
  }

  return databasePath;
}

function hasTable(client: Database, tableName: string) {
  const row = client
    .query('SELECT name FROM sqlite_master WHERE type = ? AND name = ? LIMIT 1')
    .get('table', tableName) as { name: string } | null;

  return row !== null;
}

function hasColumn(client: Database, tableName: string, columnName: string) {
  if (!hasTable(client, tableName)) {
    return false;
  }

  const rows = client.query(`PRAGMA table_info(${tableName})`).all() as Array<{ name: string }>;
  return rows.some((row) => row.name === columnName);
}

function applySqlFile(client: Database, fileName: string) {
  const sql = readFileSync(join(process.cwd(), 'drizzle', fileName), 'utf8');
  client.exec(sql);
}

let customSqliteConfigured = false;
const vectorExtensionStatus = new WeakMap<Database, boolean>();

function configureCustomSqliteRuntime() {
  if (customSqliteConfigured) {
    return;
  }

  const customSqlitePath = process.env.SQLITE_CUSTOM_LIB_PATH?.trim();
  if (process.platform === 'darwin' && customSqlitePath) {
    Database.setCustomSQLite(customSqlitePath);
  }

  customSqliteConfigured = true;
}

function loadSqliteExtensions(client: Database) {
  try {
    const customVectorExtensionPath = process.env.SQLITE_VEC_EXTENSION_PATH?.trim();

    if (customVectorExtensionPath) {
      client.loadExtension(customVectorExtensionPath);
    } else {
      loadSqliteVec(client);
    }

    vectorExtensionStatus.set(client, true);
  } catch (error) {
    vectorExtensionStatus.set(client, false);

    const reason = error instanceof Error ? error.message : 'Unknown sqlite extension error';
    console.warn(`[sqlite] sqlite-vec unavailable, falling back to table-backed vector storage: ${reason}`);
  }
}

function isVectorExtensionLoaded(client: Database) {
  return vectorExtensionStatus.get(client) ?? false;
}

function ensureLocalSqliteSchema(client: Database) {
  if (!hasTable(client, 'filing_statement_snapshot')) {
    applySqlFile(client, '0001_glossy_statement_snapshots.sql');
  }

  if (hasTable(client, 'task_run')) {
    const missingTaskColumns: Array<{ name: string; sql: string }> = [
      { name: 'stage', sql: "ALTER TABLE `task_run` ADD `stage` text NOT NULL DEFAULT 'queued';" },
      { name: 'stage_detail', sql: 'ALTER TABLE `task_run` ADD `stage_detail` text;' },
      { name: 'resource_key', sql: 'ALTER TABLE `task_run` ADD `resource_key` text;' },
      { name: 'notification_read_at', sql: 'ALTER TABLE `task_run` ADD `notification_read_at` text;' },
      { name: 'notification_silenced_at', sql: 'ALTER TABLE `task_run` ADD `notification_silenced_at` text;' }
    ];

    for (const column of missingTaskColumns) {
      if (!hasColumn(client, 'task_run', column.name)) {
        client.exec(column.sql);
      }
    }
  }

  if (!hasTable(client, 'task_stage_event')) {
    applySqlFile(client, '0003_task_stage_event_timeline.sql');
  }

  if (hasTable(client, 'watchlist_item')) {
    const missingWatchlistColumns: Array<{ name: string; sql: string }> = [
      { name: 'category', sql: 'ALTER TABLE `watchlist_item` ADD `category` text;' },
      { name: 'tags', sql: 'ALTER TABLE `watchlist_item` ADD `tags` text;' },
      { name: 'status', sql: "ALTER TABLE `watchlist_item` ADD `status` text NOT NULL DEFAULT 'backlog';" },
      { name: 'priority', sql: "ALTER TABLE `watchlist_item` ADD `priority` text NOT NULL DEFAULT 'medium';" },
      { name: 'updated_at', sql: "ALTER TABLE `watchlist_item` ADD `updated_at` text NOT NULL DEFAULT '';" },
      { name: 'last_reviewed_at', sql: 'ALTER TABLE `watchlist_item` ADD `last_reviewed_at` text;' }
    ];

    for (const column of missingWatchlistColumns) {
      if (!hasColumn(client, 'watchlist_item', column.name)) {
        client.exec(column.sql);
      }
    }

    client.exec(`
      UPDATE \`watchlist_item\`
      SET
        \`status\` = CASE
          WHEN \`status\` IS NULL OR TRIM(\`status\`) = '' THEN 'backlog'
          ELSE \`status\`
        END,
        \`priority\` = CASE
          WHEN \`priority\` IS NULL OR TRIM(\`priority\`) = '' THEN 'medium'
          ELSE \`priority\`
        END,
        \`updated_at\` = CASE
          WHEN \`updated_at\` IS NULL OR TRIM(\`updated_at\`) = '' THEN COALESCE(NULLIF(\`created_at\`, ''), CURRENT_TIMESTAMP)
          ELSE \`updated_at\`
        END;
    `);

    client.exec('CREATE INDEX IF NOT EXISTS `watchlist_user_updated_idx` ON `watchlist_item` (`user_id`, `updated_at`);');
  }

  if (hasTable(client, 'holding') && !hasColumn(client, 'holding', 'company_name')) {
    client.exec('ALTER TABLE `holding` ADD `company_name` text;');
  }

  if (!hasTable(client, 'filing_taxonomy_snapshot')) {
    applySqlFile(client, '0005_financial_taxonomy_v3.sql');
  }

  if (!hasTable(client, 'company_financial_bundle')) {
    applySqlFile(client, '0007_company_financial_bundles.sql');
  }

  if (!hasTable(client, 'research_journal_entry')) {
    client.exec(`
      CREATE TABLE IF NOT EXISTS \`research_journal_entry\` (
        \`id\` integer PRIMARY KEY AUTOINCREMENT NOT NULL,
        \`user_id\` text NOT NULL,
        \`ticker\` text NOT NULL,
        \`accession_number\` text,
        \`entry_type\` text NOT NULL,
        \`title\` text,
        \`body_markdown\` text NOT NULL,
        \`metadata\` text,
        \`created_at\` text NOT NULL,
        \`updated_at\` text NOT NULL,
        FOREIGN KEY (\`user_id\`) REFERENCES \`user\`(\`id\`) ON UPDATE no action ON DELETE cascade
      );
    `);
    client.exec('CREATE INDEX IF NOT EXISTS `research_journal_ticker_idx` ON `research_journal_entry` (`user_id`, `ticker`, `created_at`);');
    client.exec('CREATE INDEX IF NOT EXISTS `research_journal_accession_idx` ON `research_journal_entry` (`user_id`, `accession_number`);');
  }

  if (!hasTable(client, 'search_document')) {
    applySqlFile(client, '0008_search_rag.sql');
  }
}

function ensureSearchVirtualTables(client: Database) {
  client.exec(`
    CREATE VIRTUAL TABLE IF NOT EXISTS \`search_chunk_fts\` USING fts5(
      \`chunk_text\`,
      \`citation_label\`,
      \`heading_path\`,
      \`chunk_id\` UNINDEXED,
      \`document_id\` UNINDEXED,
      \`chunk_index\` UNINDEXED,
      \`scope\` UNINDEXED,
      \`user_id\` UNINDEXED,
      \`source_kind\` UNINDEXED,
      \`ticker\` UNINDEXED,
      \`accession_number\` UNINDEXED,
      \`filing_date\` UNINDEXED
    );
  `);

  if (isVectorExtensionLoaded(client)) {
    client.exec(`
      CREATE VIRTUAL TABLE IF NOT EXISTS \`search_chunk_vec\` USING vec0(
        \`chunk_id\` integer PRIMARY KEY,
        \`embedding\` float[256],
        \`scope\` text,
        \`user_id\` text,
        \`source_kind\` text,
        \`ticker\` text,
        \`accession_number\` text,
        \`filing_date\` text,
        +\`document_id\` integer,
        +\`chunk_index\` integer,
        +\`citation_label\` text
      );
    `);
    return;
  }

  client.exec(`
    CREATE TABLE IF NOT EXISTS \`search_chunk_vec\` (
      \`chunk_id\` integer PRIMARY KEY NOT NULL,
      \`embedding\` text NOT NULL,
      \`scope\` text NOT NULL,
      \`user_id\` text,
      \`source_kind\` text NOT NULL,
      \`ticker\` text,
      \`accession_number\` text,
      \`filing_date\` text,
      \`document_id\` integer NOT NULL,
      \`chunk_index\` integer NOT NULL,
      \`citation_label\` text NOT NULL
    );
  `);
  client.exec('CREATE INDEX IF NOT EXISTS `search_chunk_vec_lookup_idx` ON `search_chunk_vec` (`scope`, `user_id`, `source_kind`, `ticker`);');
}

export function getSqliteClient() {
  if (!globalThis.__fiscalSqliteClient) {
    configureCustomSqliteRuntime();
    const databasePath = getDatabasePath();

    if (databasePath !== ':memory:') {
      mkdirSync(dirname(databasePath), { recursive: true });
    }

    const client = new Database(databasePath, { create: true });
    client.exec('PRAGMA foreign_keys = ON;');
    client.exec('PRAGMA journal_mode = WAL;');
    client.exec('PRAGMA busy_timeout = 5000;');
    loadSqliteExtensions(client);
    ensureLocalSqliteSchema(client);
    ensureSearchVirtualTables(client);

    globalThis.__fiscalSqliteClient = client;
  }

  return globalThis.__fiscalSqliteClient;
}

function createDb() {
  return drizzle(getSqliteClient(), { schema });
}

export const db = globalThis.__fiscalDrizzleDb ?? createDb();

if (!globalThis.__fiscalDrizzleDb) {
  globalThis.__fiscalDrizzleDb = db;
}

export const __dbInternals = {
  configureCustomSqliteRuntime,
  ensureLocalSqliteSchema,
  ensureSearchVirtualTables,
  getDatabasePath,
  hasColumn,
  hasTable,
  isVectorExtensionLoaded,
  loadSqliteExtensions
};