<?php
declare(strict_types=1);

require_once __DIR__ . '/db.php';

try {
    match ($_SERVER['REQUEST_METHOD']) {
        'GET'    => handle_get(),
        'POST'   => handle_post(),
        'PUT'    => handle_put(),
        'DELETE' => handle_delete(),
        default  => error_out('Method not allowed', 405),
    };
} catch (PDOException $e) {
    error_out('Database error: ' . $e->getMessage(), 500);
}

// ─── GET /api/schedule.php ────────────────────────────────────────────────────

function handle_get(): never
{
    $rows = db()->query(
        'SELECT sr.id, sr.mode, sr.offset_value, sr.offset_unit,
                sr.specific_datetime, sr.created_at,
                t.id AS template_id, t.name AS template_name
         FROM scheduled_rules sr
         JOIN sms_templates t ON t.id = sr.template_id
         ORDER BY sr.created_at DESC'
    )->fetchAll();

    json_out(['rules' => $rows]);
}

// ─── POST /api/schedule.php ───────────────────────────────────────────────────
// Body: {
//   "template_id": 1,
//   "mode": "relative",          -- or "specific"
//   "offset_value": 30,          -- required for relative
//   "offset_unit": "minutes",    -- required for relative (minutes|hours|days)
//   "specific_datetime": "..."   -- required for specific (ISO 8601 or MySQL datetime)
// }

function handle_post(): never
{
    $body       = json_body();
    $templateId = (int) ($body['template_id'] ?? 0);
    $mode       = (string) ($body['mode'] ?? '');

    if ($templateId <= 0) {
        error_out('template_id is required');
    }
    if (!in_array($mode, ['relative', 'specific'], true)) {
        error_out('mode must be "relative" or "specific"');
    }

    $offsetValue  = null;
    $offsetUnit   = null;
    $specificDt   = null;

    if ($mode === 'relative') {
        $offsetValue = (int) ($body['offset_value'] ?? 0);
        $offsetUnit  = (string) ($body['offset_unit'] ?? '');

        if ($offsetValue <= 0) {
            error_out('offset_value must be a positive integer');
        }
        if (!in_array($offsetUnit, ['minutes', 'hours', 'days'], true)) {
            error_out('offset_unit must be "minutes", "hours", or "days"');
        }
    } else {
        $specificDt = (string) ($body['specific_datetime'] ?? '');
        if ($specificDt === '') {
            error_out('specific_datetime is required when mode is "specific"');
        }
        if (strtotime($specificDt) === false) {
            error_out('specific_datetime is not a valid date/time');
        }
    }

    // Verify template exists
    $check = db()->prepare('SELECT id FROM sms_templates WHERE id = :id');
    $check->execute([':id' => $templateId]);
    if (!$check->fetch()) {
        error_out('Template not found', 404);
    }

    $stmt = db()->prepare(
        'INSERT INTO scheduled_rules (template_id, mode, offset_value, offset_unit, specific_datetime)
         VALUES (:template_id, :mode, :offset_value, :offset_unit, :specific_datetime)'
    );
    $stmt->execute([
        ':template_id'       => $templateId,
        ':mode'              => $mode,
        ':offset_value'      => $offsetValue,
        ':offset_unit'       => $offsetUnit,
        ':specific_datetime' => $specificDt,
    ]);

    json_out(['id' => (int) db()->lastInsertId()], 201);
}

// ─── PUT /api/schedule.php?id=N ─────────────────────────────────────────────
// Body: same fields as POST

function handle_put(): never
{
    $id = (int) ($_GET['id'] ?? 0);
    if ($id <= 0) {
        error_out('Missing or invalid id');
    }

    $body       = json_body();
    $templateId = (int) ($body['template_id'] ?? 0);
    $mode       = (string) ($body['mode'] ?? '');

    if ($templateId <= 0) {
        error_out('template_id is required');
    }
    if (!in_array($mode, ['relative', 'specific'], true)) {
        error_out('mode must be "relative" or "specific"');
    }

    $offsetValue = null;
    $offsetUnit  = null;
    $specificDt  = null;

    if ($mode === 'relative') {
        $offsetValue = (int) ($body['offset_value'] ?? 0);
        $offsetUnit  = (string) ($body['offset_unit'] ?? '');
        if ($offsetValue <= 0) {
            error_out('offset_value must be a positive integer');
        }
        if (!in_array($offsetUnit, ['minutes', 'hours', 'days'], true)) {
            error_out('offset_unit must be "minutes", "hours", or "days"');
        }
    } else {
        $specificDt = (string) ($body['specific_datetime'] ?? '');
        if ($specificDt === '') {
            error_out('specific_datetime is required when mode is "specific"');
        }
        if (strtotime($specificDt) === false) {
            error_out('specific_datetime is not a valid date/time');
        }
    }

    $db    = db();
    $check = $db->prepare('SELECT id FROM sms_templates WHERE id = :id');
    $check->execute([':id' => $templateId]);
    if (!$check->fetch()) {
        error_out('Template not found', 404);
    }

    $stmt = $db->prepare(
        'UPDATE scheduled_rules
         SET template_id = :template_id, mode = :mode,
             offset_value = :offset_value, offset_unit = :offset_unit,
             specific_datetime = :specific_datetime
         WHERE id = :id'
    );
    $stmt->execute([
        ':template_id'       => $templateId,
        ':mode'              => $mode,
        ':offset_value'      => $offsetValue,
        ':offset_unit'       => $offsetUnit,
        ':specific_datetime' => $specificDt,
        ':id'                => $id,
    ]);

    if ($stmt->rowCount() === 0) {
        error_out('Rule not found', 404);
    }

    // Detach previous send_jobs so the updated rule fires fresh on the next
    // scheduler tick (delivery_log history is preserved via the send_jobs FK).
    $db->prepare('UPDATE send_jobs SET scheduled_rule_id = NULL WHERE scheduled_rule_id = :id')
       ->execute([':id' => $id]);

    json_out(['updated' => true]);
}

// ─── DELETE /api/schedule.php?id=N ───────────────────────────────────────────

function handle_delete(): never
{
    $id = (int) ($_GET['id'] ?? 0);
    if ($id <= 0) {
        error_out('Missing or invalid id');
    }

    $stmt = db()->prepare('DELETE FROM scheduled_rules WHERE id = :id');
    $stmt->execute([':id' => $id]);

    if ($stmt->rowCount() === 0) {
        error_out('Rule not found', 404);
    }

    json_out(['deleted' => true]);
}