import { randomUUID } from "node:crypto";
import { readFile } from "node:fs/promises";
import path from "node:path";
import process from "node:process";
import { createInterface } from "node:readline";
import pg from "pg";

const { Client } = pg;
const EXPECTED_DATABASE = "booking_test";
const REQUIRED_MIGRATION = "002_legacy_import_and_bookings";
const DEFAULT_BATCH = path.resolve(
  process.cwd(),
  "../.planning/data_import_audit/import_batch_2026_07_31"
);

async function readStandardInput() {
  const lines = createInterface({ input: process.stdin, terminal: false });
  for await (const line of lines) {
    lines.close();
    return line.trim();
  }
  throw Object.assign(new Error("Missing connection input"), {
    code: "MISSING_CONNECTION_INPUT"
  });
}

function safeError(error) {
  return {
    ok: false,
    errorCode: typeof error?.code === "string" ? error.code : "IMPORT_FAILED",
    errorMessage: typeof error?.message === "string"
      ? error.message.replace(/\s+/g, " ").slice(0, 300)
      : "Import failed"
  };
}

async function loadBatch(batchDirectory) {
  const read = async name => JSON.parse(
    await readFile(path.join(batchDirectory, name), "utf8")
  );
  const [manifest, owners, usage, rejected] = await Promise.all([
    read("manifest.json"),
    read("owners.json"),
    read("usage_legacy.json"),
    read("rejected_rows.json")
  ]);
  return { manifest, owners, usage, rejected };
}

function assertBatch(batch) {
  const { manifest, owners, usage, rejected } = batch;
  if (manifest.mode !== "local-import-preflight") {
    throw Object.assign(new Error("Unexpected import batch mode"), {
      code: "INVALID_IMPORT_BATCH"
    });
  }
  if (manifest.rules.latest_workbook_only !== true
    || manifest.rules.missing_confirmation !== "clear_or_exclude"
    || manifest.rules.legacy_applied_multiplier !== null
    || manifest.rules.legacy_rule_version !== "legacy-source") {
    throw Object.assign(new Error("Import batch rules do not match approved policy"), {
      code: "INVALID_IMPORT_BATCH_RULES"
    });
  }
  if (owners.length !== manifest.counts.owner_count
    || usage.length !== manifest.counts.accepted_usage_count
    || rejected.length !== manifest.counts.rejected_row_count) {
    throw Object.assign(new Error("Import batch counts do not match manifest"), {
      code: "INVALID_IMPORT_BATCH_COUNTS"
    });
  }
  if (manifest.checks.owner_issues.length > 0
    || manifest.checks.required_usage_issues.length > 0
    || manifest.checks.date_night_issues.length > 0
    || manifest.checks.arithmetic_issues.length > 0
    || manifest.checks.balance_chain_issues.length > 0
    || manifest.checks.room_gt_one_count !== 0
    || manifest.checks.missing_owner_rooms.length > 0) {
    throw Object.assign(new Error("Import batch contains failed preflight checks"), {
      code: "IMPORT_PREFLIGHT_FAILED"
    });
  }
}

function periodKey(roomNo, year) {
  return `${roomNo}|${year}`;
}

async function bulkInsert(client, table, columns, rows, chunkSize = 100) {
  if (rows.length === 0) return;
  for (let start = 0; start < rows.length; start += chunkSize) {
    const chunk = rows.slice(start, start + chunkSize);
    const values = [];
    const placeholders = chunk.map((row, rowIndex) => {
      const rowPlaceholders = row.map((value, columnIndex) => {
        values.push(value);
        return `$${rowIndex * columns.length + columnIndex + 1}`;
      });
      return `(${rowPlaceholders.join(", ")})`;
    });
    await client.query(
      `INSERT INTO ${table} (${columns.join(", ")}) VALUES ${placeholders.join(", ")}`,
      values
    );
  }
}

function createImportPlan(batch) {
  const { manifest, owners, usage } = batch;
  const importBatch = `legacy-${manifest.source_sha256.slice(0, 16)}`;
  const ownerIds = new Map(owners.map(owner => [owner.room_no, randomUUID()]));
  const usageByPeriod = new Map();
  for (const record of usage) {
    if (!ownerIds.has(record.owner_room_no)) {
      throw Object.assign(new Error(`Usage room is not in owner batch: ${record.owner_room_no}`), {
        code: "IMPORT_OWNER_NOT_FOUND"
      });
    }
    if (!Number.isInteger(record.period_year)) {
      throw Object.assign(new Error(`Usage period is missing: ${record.source_sheet}!${record.source_row}`), {
        code: "IMPORT_PERIOD_MISSING"
      });
    }
    const key = periodKey(record.owner_room_no, record.period_year);
    const rows = usageByPeriod.get(key) ?? [];
    rows.push(record);
    usageByPeriod.set(key, rows);
  }

  const carryByRoom = new Map();
  for (const owner of owners) {
    const rows = usageByPeriod.get(periodKey(owner.room_no, 2025)) ?? [];
    if (rows.length > 0) {
      const finalBalance = rows.at(-1).balance;
      carryByRoom.set(owner.room_no, finalBalance);
    }
  }

  const periodRows = [];
  const periodIds = new Map();
  const ledgerGrantRows = [];
  const ledgerCarryRows = [];
  for (const owner of owners) {
    const years = new Set([2026]);
    for (const record of usageByPeriod.get(periodKey(owner.room_no, 2025)) ?? []) {
      years.add(record.period_year);
    }
    for (const year of [...years].sort((left, right) => left - right)) {
      const rows = usageByPeriod.get(periodKey(owner.room_no, year)) ?? [];
      const carryForward = year === 2026 ? carryByRoom.get(owner.room_no) ?? 0 : 0;
      if (year === 2025 && rows.length > 0 && rows[0].total !== 15) {
        throw Object.assign(new Error(`2025 source Total is not 15 for ${owner.room_no}`), {
          code: "IMPORT_PERIOD_OPENING_MISMATCH"
        });
      }
      if (year === 2026 && rows.length > 0 && carryForward === 0 && rows[0].total !== 15) {
        throw Object.assign(new Error(`2026 source Total is not 15 for ${owner.room_no}`), {
          code: "IMPORT_PERIOD_OPENING_MISMATCH"
        });
      }
      const useSum = rows.reduce((sum, row) => sum + row.use, 0);
      const currentBalance = 15 + carryForward - useSum;
      const id = randomUUID();
      periodIds.set(periodKey(owner.room_no, year), id);
      periodRows.push([
        id,
        ownerIds.get(owner.room_no),
        year,
        `${year}-01-01`,
        `${year}-12-31`,
        15,
        carryForward,
        currentBalance,
        1
      ]);
      const grantLedgerId = randomUUID();
      ledgerGrantRows.push([
        grantLedgerId,
        id,
        null,
        "annual_grant",
        15,
        0,
        15
      ]);
      if (carryForward > 0) {
        ledgerCarryRows.push([
          randomUUID(),
          id,
          null,
          "carry_forward",
          carryForward,
          15,
          15 + carryForward
        ]);
      }
    }
  }

  const confirmationSet = new Set(usage.map(record => record.confirmation_no));
  const bookingRows = [...confirmationSet].sort().map(confirmation => [confirmation]);
  const usageRows = [];
  const usageIds = new Map();
  for (const record of usage) {
    const usageId = randomUUID();
    const usageKey = `${record.source_sheet}!${record.source_row}`;
    usageIds.set(usageKey, usageId);
    usageRows.push([
      usageId,
      ownerIds.get(record.owner_room_no),
      periodIds.get(periodKey(record.owner_room_no, record.period_year)),
      record.confirmation_no,
      record.check_in,
      record.check_out,
      record.night,
      record.canonical_used_room_type_code,
      record.raw_used_room_type,
      null,
      "legacy-source",
      record.use,
      record.total,
      record.balance,
      record.room,
      record.remark,
      randomUUID(),
      record.source_sheet,
      record.source_row,
      record.source_sequence,
      importBatch
    ]);
  }

  const usageLedgerRows = usage.map(record => [
    randomUUID(),
    periodIds.get(periodKey(record.owner_room_no, record.period_year)),
    usageIds.get(`${record.source_sheet}!${record.source_row}`),
    "usage",
    -record.use,
    record.total,
    record.balance
  ]);

  return {
    importBatch,
    ownerIds,
    periodIds,
    periodRows,
    bookingRows,
    ledgerGrantRows,
    ledgerCarryRows,
    usageRows,
    usageLedgerRows,
    counts: {
      ownerCount: owners.length,
      periodCount: periodRows.length,
      bookingCount: bookingRows.length,
      usageCount: usageRows.length,
      ledgerCount: ledgerGrantRows.length + ledgerCarryRows.length + usageLedgerRows.length
    }
  };
}

async function verifyEmptyTarget(client) {
  const result = await client.query(`
    SELECT
      (SELECT count(*)::integer FROM condon.owner_accounts) AS owners,
      (SELECT count(*)::integer FROM condon.entitlement_periods) AS periods,
      (SELECT count(*)::integer FROM condon.usage_records) AS usage,
      (SELECT count(*)::integer FROM condon.entitlement_ledger) AS ledger,
      (SELECT count(*)::integer FROM condon.bookings) AS bookings
  `);
  const counts = result.rows[0];
  if (Object.values(counts).some(value => Number(value) !== 0)) {
    throw Object.assign(new Error("CONDO business tables are not empty; import aborted"), {
      code: "IMPORT_REQUIRES_EMPTY_CONDON"
    });
  }
  return counts;
}

async function verifyMigration(client) {
  const result = await client.query(`
    SELECT version
    FROM condon.schema_migrations
    WHERE version = $1
  `, [REQUIRED_MIGRATION]);
  if (result.rowCount !== 1) {
    throw Object.assign(new Error(`Required migration is missing: ${REQUIRED_MIGRATION}`), {
      code: "IMPORT_SCHEMA_NOT_READY"
    });
  }
}

const batchDirectory = path.resolve(process.argv[2] ?? DEFAULT_BATCH);
const apply = process.argv.includes("--apply");
let client;
let transactionStarted = false;

try {
  const batch = await loadBatch(batchDirectory);
  assertBatch(batch);
  const plan = createImportPlan(batch);
  if (!apply) {
    process.stdout.write(`${JSON.stringify({
      ok: true,
      mode: "dry-run",
      batchDirectory,
      importBatch: plan.importBatch,
      counts: plan.counts
    }, null, 2)}\n`);
    process.exit(0);
  }

  const input = JSON.parse(await readStandardInput());
  client = new Client({
    host: input.host,
    port: input.port,
    user: input.user,
    password: input.password,
    database: input.database,
    ssl: input.ssl ? { rejectUnauthorized: false } : undefined,
    application_name: "condon_legacy_import",
    connectionTimeoutMillis: 10_000,
    query_timeout: 60_000,
    options: "-c statement_timeout=60000 -c lock_timeout=5000"
  });
  await client.connect();
  await client.query("BEGIN");
  transactionStarted = true;

  const identity = (await client.query(`
    SELECT current_database() AS database_name, current_user AS role_name
  `)).rows[0];
  if (identity.database_name !== EXPECTED_DATABASE || identity.role_name !== input.user) {
    throw Object.assign(new Error("Unexpected database or role"), {
      code: "UNEXPECTED_DATABASE"
    });
  }
  await verifyMigration(client);
  const before = await verifyEmptyTarget(client);

  const ownerRows = batch.owners.map(owner => [
    plan.ownerIds.get(owner.room_no),
    owner.account_no,
    owner.transfer_date,
    owner.name,
    owner.room_no,
    owner.purchased_room_type_code,
    owner.unit_no,
    owner.member_no
  ]);
  await bulkInsert(
    client,
    "condon.owner_accounts",
    ["id", "account_no", "transfer_date", "owner_name", "room_no", "purchased_room_type_code", "unit_no", "member_no"],
    ownerRows
  );
  await bulkInsert(
    client,
    "condon.entitlement_periods",
    ["id", "owner_account_id", "period_year", "period_start", "period_end", "annual_grant", "carry_forward", "current_balance", "row_version"],
    plan.periodRows
  );
  await bulkInsert(client, "condon.bookings", ["confirmation_no"], plan.bookingRows);
  await bulkInsert(
    client,
    "condon.entitlement_ledger",
    ["id", "entitlement_period_id", "usage_record_id", "entry_type", "delta_nights", "balance_before", "balance_after"],
    [...plan.ledgerGrantRows, ...plan.ledgerCarryRows]
  );
  await bulkInsert(
    client,
    "condon.usage_records",
    [
      "id",
      "owner_account_id",
      "entitlement_period_id",
      "confirmation_no",
      "check_in",
      "check_out",
      "night_count",
      "used_room_type_code",
      "raw_used_room_type",
      "applied_multiplier",
      "rule_version",
      "use_nights",
      "balance_before",
      "balance_after",
      "room_count",
      "remark",
      "idempotency_key",
      "source_sheet",
      "source_row",
      "source_sequence",
      "import_batch"
    ],
    plan.usageRows
  );
  await bulkInsert(
    client,
    "condon.entitlement_ledger",
    ["id", "entitlement_period_id", "usage_record_id", "entry_type", "delta_nights", "balance_before", "balance_after"],
    plan.usageLedgerRows
  );

  const afterResult = await client.query(`
    SELECT
      (SELECT count(*)::integer FROM condon.owner_accounts) AS owners,
      (SELECT count(*)::integer FROM condon.entitlement_periods) AS periods,
      (SELECT count(*)::integer FROM condon.bookings) AS bookings,
      (SELECT count(*)::integer FROM condon.usage_records) AS usage,
      (SELECT count(*)::integer FROM condon.entitlement_ledger) AS ledger,
      (SELECT coalesce(sum(use_nights), 0)::integer FROM condon.usage_records) AS use_sum,
      (SELECT coalesce(sum(current_balance), 0)::integer FROM condon.entitlement_periods WHERE period_year = 2026) AS current_balance_2026
  `);
  const after = afterResult.rows[0];
  if (Number(after.owners) !== plan.counts.ownerCount
    || Number(after.periods) !== plan.counts.periodCount
    || Number(after.bookings) !== plan.counts.bookingCount
    || Number(after.usage) !== plan.counts.usageCount
    || Number(after.ledger) !== plan.counts.ledgerCount
    || Number(after.use_sum) !== batch.manifest.counts.usage_use_sum) {
    throw Object.assign(new Error("Import post-check counts failed"), {
      code: "IMPORT_POSTCHECK_FAILED"
    });
  }

  await client.query("COMMIT");
  transactionStarted = false;
  process.stdout.write(`${JSON.stringify({
    ok: true,
    mode: "applied",
    batchDirectory,
    importBatch: plan.importBatch,
    before,
    planned: plan.counts,
    after
  }, null, 2)}\n`);
} catch (error) {
  if (client && transactionStarted) {
    await client.query("ROLLBACK").catch(() => undefined);
    transactionStarted = false;
  }
  process.stdout.write(`${JSON.stringify(safeError(error), null, 2)}\n`);
  process.exitCode = 1;
} finally {
  if (client) await client.end().catch(() => { process.exitCode = 1; });
}