import { mkdirSync } from 'node:fs';
import { dirname } from 'node:path';
import { Database } from 'bun:sqlite';
import { drizzle } from 'drizzle-orm/bun-sqlite';
import { load as loadSqliteVec } from 'sqlite-vec';
import {
  ensureFinancialIngestionSchemaHealthy,
  resolveFinancialSchemaRepairMode
} from './financial-ingestion-schema';
import { schema } from './schema';
import {
  ensureLocalSqliteSchema,
  hasColumn,
  hasTable,
  TAXONOMY_SNAPSHOT_REQUIRED_COLUMNS
} from './sqlite-schema-compat';

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;
}

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 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`);');
}

function verifyCriticalSchema(client: Database) {
  if (!hasTable(client, 'filing_taxonomy_snapshot')) {
    return;
  }

  const missingColumns: string[] = [];
  for (const columnName of TAXONOMY_SNAPSHOT_REQUIRED_COLUMNS) {
    if (!hasColumn(client, 'filing_taxonomy_snapshot', columnName)) {
      missingColumns.push(columnName);
    }
  }

  if (missingColumns.length > 0) {
    throw new Error(
      `[db] CRITICAL: Database schema is incompatible. ` +
        `filing_taxonomy_snapshot is missing columns: ${missingColumns.join(', ')}. ` +
        `Delete the database file and restart to rebuild schema.`
    );
  }
}

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);
    verifyCriticalSchema(client);
    ensureFinancialIngestionSchemaHealthy(client, {
      mode: resolveFinancialSchemaRepairMode(process.env.FINANCIAL_SCHEMA_REPAIR_MODE)
    });
    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,
  verifyCriticalSchema
};