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

//
// ## Income Statement Report (Profit & Loss)
//
// Purpose: Show financial performance (Revenue - Expenses) over a period.
//
// ---
//
// **Rule (Absolute):** Reads ONLY from `accounts` and `journal_lines` for posted entries.
// Filters for accounts of type 'revenue' and 'expense'.
//

$pdo = db();

// Optional date range filtering
$start_date = $_GET['start_date'] ?? null;
$end_date = $_GET['end_date'] ?? date('Y-m-d');

try {
    $sql = <<<SQL
    SELECT
        a.account_code,
        a.account_name,
        a.account_type,
        a.normal_balance,
        SUM(CASE
            WHEN a.normal_balance = 'debit' THEN jl.debit_amount - jl.credit_amount
            ELSE jl.credit_amount - jl.debit_amount
        END) as balance
    FROM
        accounts a
    JOIN
        journal_lines jl ON a.account_code = jl.account_code
    JOIN
        journal_entries je ON jl.journal_entry_id = je.id
    WHERE
        je.status = 'posted'
        AND a.account_type IN ('revenue', 'expense')
SQL;

    $params = [];
    if ($start_date) {
        $sql .= " AND je.entry_date >= :start_date";
        $params[':start_date'] = $start_date;
    }
    if ($end_date) {
        $sql .= " AND je.entry_date <= :end_date";
        $params[':end_date'] = $end_date;
    }

    $sql .= " GROUP BY a.account_code, a.account_name, a.account_type, a.normal_balance ORDER BY a.account_type, a.account_code";

    $stmt = $pdo->prepare($sql);
    $stmt->execute($params);
    $report_lines = $stmt->fetchAll(PDO::FETCH_ASSOC);

    // Structure the report and calculate totals
    $revenue_total = 0;
    $expense_total = 0;
    $revenues = [];
    $expenses = [];

    foreach ($report_lines as $line) {
        if ($line['account_type'] == 'revenue') {
            $revenues[] = $line;
            $revenue_total += $line['balance'];
        } else {
            $expenses[] = $line;
            $expense_total += $line['balance'];
        }
    }

    $net_income = $revenue_total - $expense_total;

    echo json_encode([
        'success' => true,
        'report_name' => 'Income Statement',
        'generated_at' => date('c'),
        'filters' => ['start_date' => $start_date, 'end_date' => $end_date],
        'data' => [
            'revenues' => $revenues,
            'expenses' => $expenses
        ],
        'summary' => [
            'total_revenue' => $revenue_total,
            'total_expense' => $expense_total,
            'net_income' => $net_income
        ]
    ]);

} catch (PDOException $e) {
    http_response_code(500);
    echo json_encode([
        'success' => false,
        'error' => 'Database error: ' . $e->getMessage()
    ]);
}