<?php
header('Content-Type: application/json');
require_once __DIR__ . '/../db/config.php';
$pdo = db();

$method = $_SERVER['REQUEST_METHOD'];

if ($method === 'POST') {
    $input = json_decode(file_get_contents('php://input'), true);
    $amount = filter_var($input['amount'] ?? 0, FILTER_VALIDATE_FLOAT); // e.g. 0.25 for 250ml
    $date = $input['date'] ?? date('Y-m-d');

    if ($amount <= 0) {
        echo json_encode(['success' => false, 'error' => 'Invalid amount']);
        exit;
    }

    try {
        // Find existing record for today
        $stmt = $pdo->prepare("SELECT id, amount FROM water_logs WHERE logged_at = ?");
        $stmt->execute([$date]);
        $row = $stmt->fetch(PDO::FETCH_ASSOC);

        if ($row) {
            $newAmount = $row['amount'] + $amount;
            $stmtUpdate = $pdo->prepare("UPDATE water_logs SET amount = ? WHERE id = ?");
            $stmtUpdate->execute([$newAmount, $row['id']]);
        } else {
            $stmtInsert = $pdo->prepare("INSERT INTO water_logs (amount, logged_at) VALUES (?, ?)");
            $stmtInsert->execute([$amount, $date]);
        }
        echo json_encode(['success' => true]);
    } catch (PDOException $e) {
        echo json_encode(['success' => false, 'error' => $e->getMessage()]);
    }
} elseif ($method === 'GET') {
    $date = $_GET['date'] ?? date('Y-m-d');
    $stmt = $pdo->prepare("SELECT amount FROM water_logs WHERE logged_at = ?");
    $stmt->execute([$date]);
    $row = $stmt->fetch(PDO::FETCH_ASSOC);
    echo json_encode(['amount' => $row ? $row['amount'] : 0]);
}