<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Dbcompare extends MY_Admin_Controller
{
    private $sourceConfig;
    private $targetConfig;

    public function __construct()
    {
        parent::__construct();

        if (!filter_var(app_env('DBCOMPARE_ENABLED', 'false'), FILTER_VALIDATE_BOOLEAN)) {
            show_404();
        }

        $this->sourceConfig = $this->readConnectionConfig('DBCOMPARE_SOURCE');
        $this->targetConfig = $this->readConnectionConfig('DBCOMPARE_TARGET');
    }

    private function readConnectionConfig($prefix)
    {
        $config = array(
            'host' => app_env($prefix . '_HOST', ''),
            'port' => (int) app_env($prefix . '_PORT', 3306),
            'user' => app_env($prefix . '_USERNAME', ''),
            'pass' => app_env($prefix . '_PASSWORD', ''),
            'db'   => app_env($prefix . '_DATABASE', '')
        );

        foreach (array('host', 'port', 'user', 'pass', 'db') as $key) {
            if (empty($config[$key])) {
                show_error('Konfigurasi Dbcompare belum lengkap.', 503);
            }
        }

        return $config;
    }

    public function sql()
    {
        $result = $this->buildSqlDiff();

        header('Content-Type: text/plain; charset=utf-8');
        echo $result['sql'];
    }

    public function sql_download()
    {
        $result = $this->buildSqlDiff();

        $filename = 'sync_structure_' . date('Ymd_His') . '.sql';
        header('Content-Type: application/sql; charset=utf-8');
        header('Content-Disposition: attachment; filename="' . $filename . '"');
        echo $result['sql'];
    }

    private function buildSqlDiff()
    {
        $source = $this->connectMysqli($this->sourceConfig);
        $target = $this->connectMysqli($this->targetConfig);

        $sqlLines = array();
        $sqlLines[] = '-- ==================================================';
        $sqlLines[] = '-- AUTO GENERATED SQL - STRUCTURE SYNC';
        $sqlLines[] = '-- Source DB : ' . $this->sourceConfig['db'] . ' (' . $this->sourceConfig['host'] . ':' . $this->sourceConfig['port'] . ')';
        $sqlLines[] = '-- Target DB : ' . $this->targetConfig['db'] . ' (' . $this->targetConfig['host'] . ':' . $this->targetConfig['port'] . ')';
        $sqlLines[] = '-- Generated : ' . date('Y-m-d H:i:s');
        $sqlLines[] = '-- Notes     : Hanya struktur (table/column/primary key/index), tanpa data';
        $sqlLines[] = '-- ==================================================';
        $sqlLines[] = '';

        $sourceTables = $this->getTables($source, $this->sourceConfig['db']);
        $targetTables = $this->getTables($target, $this->targetConfig['db']);

        foreach ($sourceTables as $tableName) {
            $safeTable = $this->escapeIdentifier($tableName);

            if (!in_array($tableName, $targetTables, true)) {
                $createSql = $this->getCreateTableSql($source, $tableName);
                $sqlLines[] = '-- --------------------------------------------------';
                $sqlLines[] = '-- CREATE TABLE: ' . $tableName;
                $sqlLines[] = '-- --------------------------------------------------';
                $sqlLines[] = $createSql . ';';
                $sqlLines[] = '';
                continue;
            }

            $sqlLines[] = '-- --------------------------------------------------';
            $sqlLines[] = '-- ALTER TABLE: ' . $tableName;
            $sqlLines[] = '-- --------------------------------------------------';

            $sourceColumns = $this->getColumns($source, $this->sourceConfig['db'], $tableName);
            $targetColumns = $this->getColumns($target, $this->targetConfig['db'], $tableName);

            // Column ADD / MODIFY
            foreach ($sourceColumns as $columnName => $sourceCol) {
                if (!isset($targetColumns[$columnName])) {
                    $sqlLines[] = 'ALTER TABLE ' . $safeTable . ' ADD COLUMN ' . $this->buildColumnDefinition($sourceCol) . ';';
                    continue;
                }

                $targetCol = $targetColumns[$columnName];
                if (!$this->isSameColumn($sourceCol, $targetCol)) {
                    $sqlLines[] = 'ALTER TABLE ' . $safeTable . ' MODIFY COLUMN ' . $this->buildColumnDefinition($sourceCol) . ';';
                }
            }

            // Primary key sync
            $sourcePk = $this->getPrimaryKeyColumns($source, $this->sourceConfig['db'], $tableName);
            $targetPk = $this->getPrimaryKeyColumns($target, $this->targetConfig['db'], $tableName);

            if ($sourcePk !== $targetPk) {
                if (!empty($targetPk)) {
                    $sqlLines[] = 'ALTER TABLE ' . $safeTable . ' DROP PRIMARY KEY;';
                }
                if (!empty($sourcePk)) {
                    $pkCols = array();
                    foreach ($sourcePk as $pkCol) {
                        $pkCols[] = $this->escapeIdentifier($pkCol);
                    }
                    $sqlLines[] = 'ALTER TABLE ' . $safeTable . ' ADD PRIMARY KEY (' . implode(', ', $pkCols) . ');';
                }
            }

            // Secondary indexes sync (add missing / different composition)
            $sourceIndexes = $this->getIndexes($source, $this->sourceConfig['db'], $tableName);
            $targetIndexes = $this->getIndexes($target, $this->targetConfig['db'], $tableName);

            foreach ($sourceIndexes as $idxName => $sourceIdx) {
                if ($idxName === 'PRIMARY') {
                    continue;
                }

                $needCreate = false;
                if (!isset($targetIndexes[$idxName])) {
                    $needCreate = true;
                } else {
                    $targetIdx = $targetIndexes[$idxName];
                    if (!$this->isSameIndex($sourceIdx, $targetIdx)) {
                        $sqlLines[] = 'ALTER TABLE ' . $safeTable . ' DROP INDEX ' . $this->escapeIdentifier($idxName) . ';';
                        $needCreate = true;
                    }
                }

                if ($needCreate) {
                    $idxCols = array();
                    foreach ($sourceIdx['columns'] as $colName) {
                        $idxCols[] = $this->escapeIdentifier($colName);
                    }

                    $idxType = $sourceIdx['non_unique'] == 0 ? 'ADD UNIQUE INDEX ' : 'ADD INDEX ';
                    $sqlLines[] = 'ALTER TABLE ' . $safeTable . ' ' . $idxType . $this->escapeIdentifier($idxName) . ' (' . implode(', ', $idxCols) . ');';
                }
            }

            $sqlLines[] = '';
        }

        $source->close();
        $target->close();

        return array('sql' => implode("\n", $sqlLines));
    }

    private function connectMysqli($config)
    {
        $conn = @new mysqli($config['host'], $config['user'], $config['pass'], $config['db'], (int)$config['port']);
        if ($conn->connect_errno) {
            show_error('Gagal konek DB ' . $config['db'] . ': ' . $conn->connect_error, 500);
        }
        $conn->set_charset('utf8');
        return $conn;
    }

    private function getTables($conn, $schema)
    {
        $sql = "SELECT TABLE_NAME
                FROM INFORMATION_SCHEMA.TABLES
                WHERE TABLE_SCHEMA = ?
                  AND TABLE_TYPE = 'BASE TABLE'
                ORDER BY TABLE_NAME";
        $stmt = $conn->prepare($sql);
        $stmt->bind_param('s', $schema);
        $stmt->execute();
        $res = $stmt->get_result();

        $tables = array();
        while ($row = $res->fetch_assoc()) {
            $tables[] = $row['TABLE_NAME'];
        }
        $stmt->close();

        return $tables;
    }

    private function getCreateTableSql($conn, $tableName)
    {
        $sql = 'SHOW CREATE TABLE ' . $this->escapeIdentifier($tableName);
        $res = $conn->query($sql);
        if (!$res) {
            return '-- ERROR: gagal ambil CREATE TABLE untuk ' . $tableName;
        }
        $row = $res->fetch_assoc();
        return isset($row['Create Table']) ? $row['Create Table'] : '-- ERROR: format SHOW CREATE TABLE tidak valid';
    }

    private function getColumns($conn, $schema, $tableName)
    {
        $sql = "SELECT COLUMN_NAME, COLUMN_TYPE, IS_NULLABLE, COLUMN_DEFAULT, EXTRA, COLUMN_COMMENT, CHARACTER_SET_NAME, COLLATION_NAME
                FROM INFORMATION_SCHEMA.COLUMNS
                WHERE TABLE_SCHEMA = ?
                  AND TABLE_NAME = ?
                ORDER BY ORDINAL_POSITION";
        $stmt = $conn->prepare($sql);
        $stmt->bind_param('ss', $schema, $tableName);
        $stmt->execute();
        $res = $stmt->get_result();

        $columns = array();
        while ($row = $res->fetch_assoc()) {
            $columns[$row['COLUMN_NAME']] = $row;
        }
        $stmt->close();

        return $columns;
    }

    private function getPrimaryKeyColumns($conn, $schema, $tableName)
    {
        $sql = "SELECT kcu.COLUMN_NAME
                FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS tc
                JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE kcu
                  ON tc.CONSTRAINT_NAME = kcu.CONSTRAINT_NAME
                 AND tc.TABLE_SCHEMA = kcu.TABLE_SCHEMA
                 AND tc.TABLE_NAME = kcu.TABLE_NAME
                WHERE tc.TABLE_SCHEMA = ?
                  AND tc.TABLE_NAME = ?
                  AND tc.CONSTRAINT_TYPE = 'PRIMARY KEY'
                ORDER BY kcu.ORDINAL_POSITION";
        $stmt = $conn->prepare($sql);
        $stmt->bind_param('ss', $schema, $tableName);
        $stmt->execute();
        $res = $stmt->get_result();

        $pk = array();
        while ($row = $res->fetch_assoc()) {
            $pk[] = $row['COLUMN_NAME'];
        }
        $stmt->close();

        return $pk;
    }

    private function getIndexes($conn, $schema, $tableName)
    {
        $sql = "SELECT INDEX_NAME, NON_UNIQUE, SEQ_IN_INDEX, COLUMN_NAME
                FROM INFORMATION_SCHEMA.STATISTICS
                WHERE TABLE_SCHEMA = ?
                  AND TABLE_NAME = ?
                ORDER BY INDEX_NAME, SEQ_IN_INDEX";
        $stmt = $conn->prepare($sql);
        $stmt->bind_param('ss', $schema, $tableName);
        $stmt->execute();
        $res = $stmt->get_result();

        $indexes = array();
        while ($row = $res->fetch_assoc()) {
            $idxName = $row['INDEX_NAME'];
            if (!isset($indexes[$idxName])) {
                $indexes[$idxName] = array(
                    'non_unique' => (int)$row['NON_UNIQUE'],
                    'columns' => array()
                );
            }
            $indexes[$idxName]['columns'][] = $row['COLUMN_NAME'];
        }
        $stmt->close();

        return $indexes;
    }

    private function buildColumnDefinition($col)
    {
        $def = $this->escapeIdentifier($col['COLUMN_NAME']) . ' ' . $col['COLUMN_TYPE'];

        $def .= ($col['IS_NULLABLE'] === 'NO') ? ' NOT NULL' : ' NULL';

        if ($col['COLUMN_DEFAULT'] !== null) {
            if (strtoupper($col['COLUMN_DEFAULT']) === 'CURRENT_TIMESTAMP') {
                $def .= ' DEFAULT CURRENT_TIMESTAMP';
            } else {
                $def .= " DEFAULT '" . $this->escapeStringValue($col['COLUMN_DEFAULT']) . "'";
            }
        } elseif ($col['IS_NULLABLE'] === 'YES') {
            $def .= ' DEFAULT NULL';
        }

        if (!empty($col['EXTRA'])) {
            $def .= ' ' . strtoupper($col['EXTRA']);
        }

        if (!empty($col['COLUMN_COMMENT'])) {
            $def .= " COMMENT '" . $this->escapeStringValue($col['COLUMN_COMMENT']) . "'";
        }

        return $def;
    }

    private function isSameColumn($a, $b)
    {
        return (
            strtolower((string)$a['COLUMN_TYPE']) === strtolower((string)$b['COLUMN_TYPE']) &&
            (string)$a['IS_NULLABLE'] === (string)$b['IS_NULLABLE'] &&
            (string)$a['COLUMN_DEFAULT'] === (string)$b['COLUMN_DEFAULT'] &&
            strtolower((string)$a['EXTRA']) === strtolower((string)$b['EXTRA']) &&
            (string)$a['COLUMN_COMMENT'] === (string)$b['COLUMN_COMMENT']
        );
    }

    private function isSameIndex($a, $b)
    {
        return (
            (int)$a['non_unique'] === (int)$b['non_unique'] &&
            implode(',', $a['columns']) === implode(',', $b['columns'])
        );
    }

    private function escapeIdentifier($name)
    {
        return '`' . str_replace('`', '``', $name) . '`';
    }

    private function escapeStringValue($str)
    {
        return str_replace("'", "''", (string)$str);
    }
}