<?php
header('Content-Type: application/json');
require_once 'class/db-functions.php';

ini_set('display_errors', '0');
error_reporting(E_ALL);

$response = ["success" => false, "message" => ""];

try {
    if ($_SERVER["REQUEST_METHOD"] !== "POST") {
        throw new Exception("Invalid request method.");
    }

    $input = json_decode(file_get_contents('php://input'), true);

    $template_id = isset($input['template_id']) ? intval($input['template_id']) : null;
    $schemajson  = isset($input['schemajson']) ? trim($input['schemajson']) : '';

    if (empty($template_id) || empty($schemajson)) {
        throw new Exception("All fields marked with * are required, including schemajson.");
    }

    $decoded_json = json_decode($schemajson, true);

    if (json_last_error() !== JSON_ERROR_NONE) {
        throw new Exception("Invalid JSON format for schemajson.");
    }

    $db = DBHandlerSelect::getInstance();
    $pdo = $db->getConnection();

    $stmt = $pdo->prepare("SELECT target_table FROM excel_templates WHERE id = ?");
    $stmt->execute([$template_id]);
    $template = $stmt->fetch(PDO::FETCH_ASSOC);

    if (!$template) {
        throw new Exception("Template not found.");
    }

    $target_table = $template['target_table'];

    $schema_id = $decoded_json['IdSchemaCustomFields'] ?? null;
    $schema_fields = $decoded_json['SchemiCustomFieldsDettagli'] ?? [];

    if (empty($schema_id)) {
        throw new Exception("Schema ID not found in schemajson.");
    }

    if (empty($schema_fields)) {
        throw new Exception("No fields found in schema.");
    }

    $pdo->beginTransaction();

    /*
     * 1) Update raw schema JSON in excel_templates
     */
    $stmt = $pdo->prepare("
        UPDATE excel_templates
        SET schemajson = ?, updated_at = NOW()
        WHERE id = ?
    ");
    $stmt->execute([$schemajson, $template_id]);

    /*
     * Prepare reusable statements
     */

    // Check if mapping already exists
    $checkStmt = $pdo->prepare("
        SELECT id, data_type
        FROM template_mapping
        WHERE template_id = ?
        AND field_id = ?
        LIMIT 1
    ");

    // Insert new field
    $insertStmt = $pdo->prepare("
        INSERT INTO template_mapping (
            template_id,
            schema_id,
            field_id,
            data_type,
            is_required,
            default_value,
            has_list,
            length,
            decimals,
            min_value,
            max_value,
            default_curr_date,
            tablename,
            field_label
        ) VALUES (
            :template_id,
            :schema_id,
            :field_id,
            :data_type,
            :is_required,
            :default_value,
            :has_list,
            :length,
            :decimals,
            :min_value,
            :max_value,
            :default_curr_date,
            :tablename,
            :field_label
        )
    ");

    // Update existing field WITHOUT clearing manual_default
    $updateSameTypeStmt = $pdo->prepare("
        UPDATE template_mapping
        SET
            schema_id = :schema_id,
            data_type = :data_type,
            is_required = :is_required,
            default_value = :default_value,
            has_list = :has_list,
            length = :length,
            decimals = :decimals,
            min_value = :min_value,
            max_value = :max_value,
            default_curr_date = :default_curr_date,
            tablename = :tablename,
            field_label = :field_label
        WHERE id = :id
    ");

    // Update existing field AND clear user-entered value if type changed
    $updateChangedTypeStmt = $pdo->prepare("
        UPDATE template_mapping
        SET
            schema_id = :schema_id,
            data_type = :data_type,
            is_required = :is_required,
            default_value = :default_value,
            has_list = :has_list,
            length = :length,
            decimals = :decimals,
            min_value = :min_value,
            max_value = :max_value,
            default_curr_date = :default_curr_date,
            tablename = :tablename,
            field_label = :field_label,

            manual_default = NULL,
            auto_value = 'none'

        WHERE id = :id
    ");

    $currentFieldIds = [];

    /*
     * 2) Insert new fields and update existing fields
     */
    foreach ($schema_fields as $field) {
        $custom_field = $field['CustomField'] ?? [];

        if (empty($custom_field['IdCustomField'])) {
            continue;
        }

        $fieldId = (int)$custom_field['IdCustomField'];
        $currentFieldIds[] = $fieldId;

        $newDataType = $custom_field['Tipo'] ?? 'Testo';

        $data = [
            ':schema_id'         => $schema_id,
            ':data_type'         => $newDataType,
            ':is_required'       => !empty($custom_field['ObbligatorioWeb']) ? 1 : 0,
            ':default_value'     => $custom_field['ValoreDefault'] ?? null,
            ':has_list'          => !empty($custom_field['Elenco']) ? 1 : 0,
            ':length'            => $custom_field['Lunghezza'] ?? 0,
            ':decimals'          => $custom_field['Decimali'] ?? 0,
            ':min_value'         => $custom_field['Minimo'] ?? null,
            ':max_value'         => $custom_field['Massimo'] ?? null,
            ':default_curr_date' => !empty($custom_field['DefaultCurrDate']) ? 1 : 0,
            ':tablename'         => $target_table,
            ':field_label'       => $custom_field['TitoloTraduzione'] ?? ''
        ];

        $checkStmt->execute([$template_id, $fieldId]);
        $existing = $checkStmt->fetch(PDO::FETCH_ASSOC);

        if (!$existing) {
            // New field: insert it
            $insertData = $data;
            $insertData[':template_id'] = $template_id;
            $insertData[':field_id'] = $fieldId;

            $insertStmt->execute($insertData);
        } else {
            // Existing field: update schema details
            $oldDataType = $existing['data_type'] ?? '';

            $updateData = $data;
            $updateData[':id'] = (int)$existing['id'];

            if ($oldDataType !== $newDataType) {
                // Type changed: clear manual value because it may no longer be valid
                $updateChangedTypeStmt->execute($updateData);
            } else {
                // Same type: keep manual_default, excel/json mapping, visibility, main field, etc.
                $updateSameTypeStmt->execute($updateData);
            }
        }
    }

    /*
     * 3) Remove fields no longer present in the schema
     */
    $currentFieldIds = array_values(array_unique(array_filter($currentFieldIds)));

    if (!empty($currentFieldIds)) {
        $placeholders = implode(',', array_fill(0, count($currentFieldIds), '?'));

        $deleteParams = array_merge([$template_id], $currentFieldIds);

        $deleteStmt = $pdo->prepare("
            DELETE FROM template_mapping
            WHERE template_id = ?
            AND field_id NOT IN ($placeholders)
        ");
        $deleteStmt->execute($deleteParams);
    }

    $pdo->commit();

    $response["success"] = true;
    $response["message"] = "Schema JSON updated, mappings synchronized, removed fields deleted, and changed fields updated successfully.";

} catch (Exception $e) {
    if (isset($pdo) && $pdo->inTransaction()) {
        $pdo->rollback();
    }

    $response["message"] = $e->getMessage();
}

echo json_encode($response);