<?php
/**
 * API Endpoint: Validate Transmission Time
 * Checks if a transmission falls within an active block
 */

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

use Dotenv\Dotenv;

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

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

if (!isLoggedIn()) {
    http_response_code(401);
    echo json_encode(['success' => false, 'error' => 'Niet geautoriseerd.']);
    exit;
}

try {
    $db = getDbConnection();
    
    // Get POST data
    $input = json_decode(file_get_contents('php://input'), true);
    
    if (!$input) {
        $input = $_POST;
    }
    
    // Validate required fields
    $required = ['channel', 'start_date', 'start_time', 'duration'];
    foreach ($required as $field) {
        if (empty($input[$field])) {
            jsonResponse([
                'valid' => false,
                'error' => "Missing required field: $field"
            ], 400);
        }
    }
    
    $channel = $input['channel'];
    $startDate = $input['start_date'];
    $startTime = $input['start_time'];
    $duration = $input['duration'];
    
    // Calculate end time
    $endTime = addTimeToTime($startTime, $duration);
    
    // Ensure daily blocks exist
    ensureDailyBlocks($db, $startDate, $startDate);
    
    // Get all blocks for this channel and date
    $stmt = $db->prepare("
        SELECT * FROM daily_blocks 
        WHERE block_date = ? AND channel = ?
        ORDER BY actual_start_time
    ");
    $stmt->execute([$startDate, $channel]);
    $blocks = $stmt->fetchAll();
    
    if (empty($blocks)) {
        jsonResponse([
            'valid' => false,
            'error' => "Geen actief blok gevonden voor {$channel} op {$startDate}",
            'blocks' => []
        ]);
    }
    
    // Check if transmission falls within any block
    $withinBlock = false;
    $matchingBlock = null;
    
    foreach ($blocks as $block) {
        $blockStart = $block['actual_start_time'];
        $blockEnd = $block['actual_end_time'] ?? '23:59:59';
        
        // Handle overnight blocks
        $isOvernight = $blockEnd < $blockStart;
        
        if ($isOvernight) {
            // For overnight blocks, check if time is after start OR before end
            if ($startTime >= $blockStart || $startTime < $blockEnd) {
                // Also check end time
                if ($endTime <= $blockEnd || $endTime >= $blockStart) {
                    $withinBlock = true;
                    $matchingBlock = $block;
                    break;
                }
            }
        } else {
            // Normal block: check if both start and end are within block
            if ($startTime >= $blockStart && $endTime <= $blockEnd) {
                $withinBlock = true;
                $matchingBlock = $block;
                break;
            }
        }
    }
    
    if ($withinBlock) {
        jsonResponse([
            'valid' => true,
            'message' => 'Uitzending valt binnen blok',
            'block' => $matchingBlock
        ]);
    } else {
        // Find closest block for helpful error message
        $closestBlock = $blocks[0];
        $errorMessage = "Uitzending valt buiten blok tijden. ";
        $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([
            'valid' => false,
            'error' => $errorMessage,
            'blocks' => $blocks,
            'attempted_time' => $startTime . ' - ' . $endTime
        ]);
    }
    
} catch (Exception $e) {
    jsonResponse([
        'valid' => false,
        'error' => $e->getMessage()
    ], 500);
}