<?php
/**
 * API Endpoint: Update Transmission
 * Updates an existing transmission (drag-and-drop, time changes)
 */

require_once __DIR__ . '/../vendor/autoload.php';
require_once __DIR__ . '/../helpers.php';

use Dotenv\Dotenv;

$dotenv = Dotenv::createImmutable(__DIR__ . '/..');
$dotenv->load();

header('Content-Type: application/json');

try {
    $db = getDbConnection();
    
    // Get POST data
    $input = json_decode(file_get_contents('php://input'), true);
    
    if (!$input) {
        $input = $_POST;
    }
    
    // Validate required fields
    if (empty($input['id'])) {
        jsonResponse([
            'success' => false,
            'error' => 'Missing transmission ID'
        ], 400);
    }
    
    // Get existing transmission
    $stmt = $db->prepare("
        SELECT t.*, c.duration 
        FROM transmissions t
        JOIN commercials c ON t.commercial_id = c.id
        WHERE t.id = ?
    ");
    $stmt->execute([$input['id']]);
    $transmission = $stmt->fetch();
    
    if (!$transmission) {
        jsonResponse([
            'success' => false,
            'error' => 'Transmission not found'
        ], 404);
    }
    
    // Prepare update data
    $updates = [];
    $params = [];
    
    if (isset($input['start_date']) && isValidDate($input['start_date'])) {
        $updates[] = 'start_date = ?';
        $params[] = $input['start_date'];
    } else {
        $params[] = $transmission['start_date'];
    }
    
    if (isset($input['start_time']) && isValidTime($input['start_time'])) {
        $updates[] = 'start_time = ?';
        $params[] = $input['start_time'];
    } else {
        $params[] = $transmission['start_time'];
    }
    
    if (isset($input['channel'])) {
        $updates[] = 'channel = ?';
        $params[] = $input['channel'];
    } else {
        $params[] = $transmission['channel'];
    }
    
    // Check for overlaps with new position
    $checkDate = $params[0];
    $checkTime = $params[1];
    $checkChannel = $params[2];
    $endTime = addTimeToTime($checkTime, $transmission['duration']);
    
    // Validate that transmission falls within a block (inline to avoid curl issues)
    ensureDailyBlocks($db, $checkDate, $checkDate);
    
    $stmt = $db->prepare("
        SELECT * FROM daily_blocks
        WHERE block_date = ? AND channel = ?
        ORDER BY actual_start_time
    ");
    $stmt->execute([$checkDate, $checkChannel]);
    $blocks = $stmt->fetchAll();
    
    $withinBlock = false;
    foreach ($blocks as $block) {
        $blockStart = $block['actual_start_time'];
        $blockEnd = $block['actual_end_time'] ?? '23:59:59';
        
        // Handle overnight blocks
        $isOvernight = $blockEnd < $blockStart;
        
        if ($isOvernight) {
            if ($checkTime >= $blockStart || $checkTime < $blockEnd) {
                if ($endTime <= $blockEnd || $endTime >= $blockStart) {
                    $withinBlock = true;
                    break;
                }
            }
        } else {
            if ($checkTime >= $blockStart && $endTime <= $blockEnd) {
                $withinBlock = true;
                break;
            }
        }
    }
    
    if (!$withinBlock) {
        $errorMessage = "Uitzending valt buiten blok tijden. ";
        if (!empty($blocks)) {
            $errorMessage .= "Beschikbare blokken: ";
            foreach ($blocks as $block) {
                $blockStart = substr($block['actual_start_time'], 0, 5);
                $blockEnd = $block['actual_end_time'] ? substr($block['actual_end_time'], 0, 5) : '∞';
                $errorMessage .= "{$blockStart}-{$blockEnd}, ";
            }
            $errorMessage = rtrim($errorMessage, ', ');
        }
        
        jsonResponse([
            'success' => false,
            'error' => $errorMessage,
            'attempted_time' => $checkTime . ' - ' . $endTime
        ], 400);
    }
    
    $stmt = $db->prepare("
        SELECT t.id, t.start_time, t.duration, c.title
        FROM transmissions t
        JOIN commercials c ON t.commercial_id = c.id
        WHERE t.start_date = ? 
        AND t.channel = ?
        AND t.id != ?
    ");
    $stmt->execute([$checkDate, $checkChannel, $input['id']]);
    $existing = $stmt->fetchAll();
    
    foreach ($existing as $tx) {
        $txEnd = addTimeToTime($tx['start_time'], $tx['duration']);
        if (timeRangesOverlap($checkTime, $endTime, $tx['start_time'], $txEnd)) {
            jsonResponse([
                'success' => false,
                'error' => "Overlap detected with: {$tx['title']} ({$tx['start_time']} - {$txEnd})",
                'overlap' => true
            ], 409);
        }
    }
    
    // Mark as pending sync if changed
    $updates[] = "api_status = 'pending'";
    
    // Build and execute update query
    if (!empty($updates)) {
        $sql = "UPDATE transmissions SET " . implode(', ', $updates) . " WHERE id = ?";
        $params[] = $input['id'];
        
        $stmt = $db->prepare($sql);
        $stmt->execute($params);
    }
    
    // Get updated transmission
    $stmt = $db->prepare("
        SELECT 
            t.*,
            c.title,
            c.color_code,
            c.series_code
        FROM transmissions t
        JOIN commercials c ON t.commercial_id = c.id
        WHERE t.id = ?
    ");
    $stmt->execute([$input['id']]);
    $updated = $stmt->fetch();
    
    jsonResponse([
        'success' => true,
        'message' => 'Transmission updated successfully',
        'transmission' => $updated
    ]);
    
} catch (Exception $e) {
    jsonResponse([
        'success' => false,
        'error' => $e->getMessage()
    ], 500);
}