<?php
declare(strict_types=1);

header('Content-Type: application/json; charset=utf-8');

// Debug logging
$debugLog = __DIR__ . '/../../_save_learning_debug.log';
$rawBody = file_get_contents('php://input');
$logEntry = "[" . date('Y-m-d H:i:s') . "] REQUEST START\n";
$logEntry .= "POST Data (\$_POST): " . json_encode($_POST, JSON_UNESCAPED_UNICODE) . "\n";
$logEntry .= "Raw Body: " . $rawBody . "\n";
file_put_contents($debugLog, $logEntry, FILE_APPEND);

try {
    if (session_status() === PHP_SESSION_NONE) {
        session_start();
    }

    require_once __DIR__ . '/../db_conn.php';
    $pdo = db_conn();

    $payload = [];
    if (is_string($rawBody) && $rawBody !== '') {
        $decoded = json_decode($rawBody, true);
        if (is_array($decoded)) {
            $payload = $decoded;
        }
    }

    if (empty($payload)) {
        $payload = $_POST;
    }

    $logEntry = "Payload: " . json_encode($payload, JSON_UNESCAPED_UNICODE) . "\n";
    file_put_contents($debugLog, $logEntry, FILE_APPEND);

    $sessionMemberId = trim((string)($_SESSION['member_id'] ?? ''));
    $memberId = $sessionMemberId;
    if ($memberId === '') {
        file_put_contents($debugLog, "ERROR: member_id is empty\n", FILE_APPEND);
        http_response_code(401);
        echo json_encode([
            'success' => false,
            'message' => 'not_logged_in',
        ], JSON_UNESCAPED_UNICODE);
        exit;
    }

    $sessionSysCompCode = trim((string)($_SESSION['sys_comp_code'] ?? ''));
    if ($sessionSysCompCode === '') {
        file_put_contents($debugLog, "ERROR: sys_comp_code is empty in session for member_id={$memberId}\n", FILE_APPEND);
        http_response_code(401);
        echo json_encode([
            'success' => false,
            'message' => 'sys_comp_code_missing',
        ], JSON_UNESCAPED_UNICODE);
        exit;
    }

    $contentIdRaw = trim((string)($payload['content_id'] ?? ''));
    if ($contentIdRaw === '') {
        file_put_contents($debugLog, "ERROR: content_id empty\n", FILE_APPEND);
        echo json_encode([
            'success' => false,
            'message' => 'content_id가 올바르지 않습니다.',
        ], JSON_UNESCAPED_UNICODE);
        exit;
    }

    $toInt = static function ($value): int {
        if ($value === null || $value === '') {
            return 0;
        }
        return max(0, (int)$value);
    };

    $watchTm = $toInt($payload['watch_tm'] ?? 0);
    $contentTmInput = $toInt($payload['content_tm'] ?? 0);
    $allTmInput = $toInt($payload['all_tm'] ?? 0);
    $allTmIncrement = $toInt($payload['all_tm_increment'] ?? 0);

    $rawCompleted = (string)($payload['completed'] ?? '0');
    $isCompleted = in_array($rawCompleted, ['1', 'true', 'TRUE', 'y', 'Y', 'on', 'ON'], true);

    $rawWatching = (string)($payload['is_watching'] ?? 'N');
    $isWatching = in_array($rawWatching, ['1', 'true', 'TRUE', 'y', 'Y', 'on', 'ON', 'Y'], true) ? 'Y' : 'N';

    $stmtContent = $pdo->prepare(
        "SELECT content_id
         FROM edu_contents
         WHERE content_id = ?
         LIMIT 1"
    );
    $stmtContent->execute([$contentIdRaw]);
    $contentRow = $stmtContent->fetch(PDO::FETCH_ASSOC);

    $resolvedContentId = $contentRow['content_id'] ?? null;
    $defaultContentTm = 0;

    if (!$resolvedContentId && preg_match('/^[0-9]+$/', $contentIdRaw)) {
        $stmtLegacy = $pdo->prepare(
            "SELECT content_id
             FROM edu_contents
             WHERE content_id LIKE ?
             ORDER BY content_id DESC"
        );
        $stmtLegacy->execute([$contentIdRaw . '-%']);
        $legacyRows = $stmtLegacy->fetchAll(PDO::FETCH_ASSOC);
        if (count($legacyRows) === 1) {
            $resolvedContentId = $legacyRows[0]['content_id'];
            $defaultContentTm = 0;
        }
    }

    if (!$resolvedContentId) {
        file_put_contents($debugLog, "ERROR: content_id not found in edu_contents - requested={$contentIdRaw}\n", FILE_APPEND);
        echo json_encode([
            'success' => false,
            'message' => 'edu_contents에 존재하지 않는 content_id입니다.',
        ], JSON_UNESCAPED_UNICODE);
        exit;
    }

    $payloadSysCompCode = trim((string)($payload['sys_comp_code'] ?? ''));
    if ($payloadSysCompCode !== '' && $payloadSysCompCode !== $sessionSysCompCode) {
        file_put_contents($debugLog, "ERROR: sys_comp_code mismatch (session={$sessionSysCompCode}, payload={$payloadSysCompCode}) for member_id={$memberId}\n", FILE_APPEND);
        http_response_code(403);
        echo json_encode([
            'success' => false,
            'message' => 'sys_comp_code_mismatch',
        ], JSON_UNESCAPED_UNICODE);
        exit;
    }

    $sysCompCode = $sessionSysCompCode;
    $stmtUser = $pdo->prepare('SELECT 1 FROM edu_users WHERE member_id = ? AND sys_comp_code = ? LIMIT 1');
    $stmtUser->execute([$memberId, $sysCompCode]);
    $userExists = (bool)$stmtUser->fetchColumn();

    if (!$userExists) {
        file_put_contents($debugLog, "ERROR: edu_users row not found for member_id={$memberId}, sys_comp_code={$sysCompCode}\n", FILE_APPEND);
        echo json_encode([
            'success' => false,
            'message' => 'edu_users에 회원 정보가 없어 학습이력을 저장할 수 없습니다.',
            'data' => [
                'member_id' => $memberId,
                'session_member_id' => $sessionMemberId,
                'sys_comp_code' => $sysCompCode,
            ],
        ], JSON_UNESCAPED_UNICODE);
        exit;
    }

    $contentTm = max($contentTmInput, $defaultContentTm);
    $watchTm = min($watchTm, $contentTm > 0 ? $contentTm : $watchTm);

    $stmtCurrent = $pdo->prepare(
        "SELECT watch_tm, content_tm, all_tm, completed_at
         FROM edu_learning_histories
         WHERE member_id = ?
           AND sys_comp_code = ?
           AND content_id = ?
         LIMIT 1"
    );
    $stmtCurrent->execute([$memberId, $sysCompCode, $resolvedContentId]);
    $currentRow = $stmtCurrent->fetch(PDO::FETCH_ASSOC) ?: null;

    $prevWatchTm = (int)($currentRow['watch_tm'] ?? 0);
    $prevContentTm = (int)($currentRow['content_tm'] ?? 0);
    $prevAllTm = (int)($currentRow['all_tm'] ?? 0);
    $prevCompletedAt = $currentRow['completed_at'] ?? null;


    $effectiveContentTm = max($contentTm, $prevContentTm);
    $effectiveWatchTm = max($watchTm, $prevWatchTm);
    if ($effectiveContentTm > 0) {
        $effectiveWatchTm = min($effectiveWatchTm, $effectiveContentTm);
    }

    $deltaWatchTm = max(0, $effectiveWatchTm - $prevWatchTm);
    $effectiveAllTm = max($prevAllTm + $allTmIncrement, $allTmInput, $prevAllTm + $deltaWatchTm);

    // 90% 이상 시청 시 완료 처리
    $completionByTime = ($effectiveContentTm > 0) && ($effectiveWatchTm >= 0.9 * $effectiveContentTm);
    $completedAt = ($isCompleted || $completionByTime) ? ($prevCompletedAt ?: date('Y-m-d H:i:s')) : null;

    if ($currentRow) {
        $stmtSave = $pdo->prepare(
            "UPDATE edu_learning_histories
             SET watch_tm = ?,
                 content_tm = ?,
                 all_tm = ?,
                 completed_at = ?,
                 is_watching = ?,
                 last_viewed_at = NOW()
             WHERE member_id = ?
               AND sys_comp_code = ?
               AND content_id = ?"
        );
        $stmtSave->execute([
            $effectiveWatchTm,
            $effectiveContentTm,
            $effectiveAllTm,
            $completedAt,
            $isWatching,
            $memberId,
            $sysCompCode,
            $resolvedContentId,
        ]);
    } else {
        $logEntry = "No existing row found. Attempting INSERT with data: member_id=$memberId, sys_comp_code=$sysCompCode, content_id=$resolvedContentId, watch_tm=$effectiveWatchTm, all_tm=$effectiveAllTm\n";
        file_put_contents($debugLog, $logEntry, FILE_APPEND);
        
        try {
            $stmtSave = $pdo->prepare(
                "INSERT INTO edu_learning_histories
                    (member_id, sys_comp_code, content_id, first_viewed_at, last_viewed_at, watch_tm, content_tm, all_tm, completed_at, is_watching)
                 VALUES
                    (?, ?, ?, NOW(), NOW(), ?, ?, ?, ?, ?)"
            );
            $stmtSave->execute([
                $memberId,
                $sysCompCode,
                $resolvedContentId,
                $effectiveWatchTm,
                $effectiveContentTm,
                $effectiveAllTm,
                $completedAt,
                $isWatching,
            ]);
            $logEntry = "INSERT successful\n";
            file_put_contents($debugLog, $logEntry, FILE_APPEND);
        } catch (PDOException $e) {
            $logEntry = "INSERT failed with exception: " . $e->getCode() . " - " . $e->getMessage() . "\n";
            file_put_contents($debugLog, $logEntry, FILE_APPEND);
            
            if ((string)$e->getCode() !== '23000') {
                throw $e;
            }

            // 동시 저장 경합으로 동일 PK insert가 충돌하면 content_id 기준 update로 재시도
            $logEntry = "Conflict detected. Retrying with UPDATE...\n";
            file_put_contents($debugLog, $logEntry, FILE_APPEND);
            
            $stmtRetry = $pdo->prepare(
                "UPDATE edu_learning_histories
                 SET watch_tm = ?,
                     content_tm = ?,
                     all_tm = ?,
                     completed_at = ?,
                     is_watching = ?,
                     last_viewed_at = NOW()
                 WHERE member_id = ?
                   AND sys_comp_code = ?
                   AND content_id = ?"
            );
            $stmtRetry->execute([
                $effectiveWatchTm,
                $effectiveContentTm,
                $effectiveAllTm,
                $completedAt,
                $isWatching,
                $memberId,
                $sysCompCode,
                $resolvedContentId,
            ]);
            
            $logEntry = "UPDATE (retry) completed\n";
            file_put_contents($debugLog, $logEntry, FILE_APPEND);
        }
    }

    echo json_encode([
        'success' => true,
        'data' => [
            'member_id' => $memberId,
            'sys_comp_code' => $sysCompCode,
            'content_id' => $resolvedContentId,
            'requested_content_id' => $contentIdRaw,
            'watch_tm' => $effectiveWatchTm,
            'content_tm' => $effectiveContentTm,
            'all_tm' => $effectiveAllTm,
            'completed' => $completedAt !== null,
            'completed_at' => $completedAt,
            'is_watching' => $isWatching,
        ],
    ], JSON_UNESCAPED_UNICODE);
    file_put_contents($debugLog, "SUCCESS: saved member_id={$memberId}, sys_comp_code={$sysCompCode}, content_id={$resolvedContentId}, watch_tm={$effectiveWatchTm}, all_tm={$effectiveAllTm}, is_watching={$isWatching}\n", FILE_APPEND);
} catch (Throwable $e) {
    file_put_contents($debugLog, "FATAL: " . $e->getCode() . " - " . $e->getMessage() . "\n", FILE_APPEND);
    http_response_code(500);
    echo json_encode([
        'success' => false,
        'message' => $e->getMessage(),
    ], JSON_UNESCAPED_UNICODE);
}