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) {
  const customVectorExtensionPath =
    process.env.SQLITE_VEC_EXTENSION_PATH?.trim();
  const customSqlitePath = process.env.SQLITE_CUSTOM_LIB_PATH?.trim();

  try {
    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";
    if (customSqlitePath || customVectorExtensionPath) {
      console.warn(
        `[sqlite] sqlite-vec native extension load failed (SQLITE_CUSTOM_LIB_PATH=${customSqlitePath ?? "unset"}, SQLITE_VEC_EXTENSION_PATH=${customVectorExtensionPath ?? "package default"}). Falling back to table-backed vector storage: ${reason}`,
      );
      return;
    }

    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,
};