<?php
/**
 * 财务 / 账本（v24 用户第 15 条）
 *
 * 用户原话：「增加财务模块，用户可以添加自己的财务状况，例如存款、基金、保险、房子、车子等，
 *            输入金额，最后给计算出所有的资金总数。这个模块，要先创建一个家庭，或者说，
 *            创建一个账本，这个账本，可以共享给某个人，共享后，这个人就可以往这个账本加入账目，
 *            这样，双方都可以看到所有的账目，最后计算出总数，这就是一个家庭的总账目。」
 *
 * 所以模型是两层：
 *   **账本（ledger）** —— 一个家庭的总账；可以共享给某个人（可读 / 可写）。
 *   **账目（ledger_entries）** —— 一笔资产/负债：存款、基金、保险、房子、车子…
 *
 * 三个设计决定：
 *   ① 金额一律用**分**存（BIGINT），不用浮点。
 *      钱是最不能容忍 0.1+0.2=0.30000000000000004 的地方。
 *      对外一律走 amountYuan() 转成元来显示，四舍五入到分。
 *   ② 分清「资产 / 负债」：房子车子是资产，房贷车贷是负债。
 *      只把资产加总会把"欠着银行两百万"这件事藏起来。净资产 = 资产 − 负债。
 *   ③ 账本为空时**自动建一个默认账本**并把它共享给建号的人，
 *      否则新用户进财务页一片空白、还不知道要先"创建家庭"。
 */

declare(strict_types=1);

namespace App;

final class Ledger
{
    /** 账目分类：key => [名字, 是资产还是负债, 图标] */
    public const KINDS = [
        'deposit'  => ['存款',   'asset', '🏦'],
        'fund'     => ['基金',   'asset', '📈'],
        'stock'    => ['股票',   'asset', '📊'],
        'insurance'=> ['保险',   'asset', '🛡'],
        'house'    => ['房子',   'asset', '🏠'],
        'car'      => ['车子',   'asset', '🚗'],
        'cash'     => ['现金',   'asset', '💵'],
        'loan'     => ['贷款',   'debt',  '📉'],
        'credit'   => ['信用卡', 'debt',  '💳'],
        'other'    => ['其它',   'asset', '📦'],
    ];

    public const PERM = ['read' => '只读', 'write' => '可写'];

    /**
     * 我能看到的账本 = 我建的 + 共享给我的。
     * 全都带上 my_perm（我在这本账上能做什么），上层不必再查一次。
     */
    public static function mine(int $familyId, int $personId): array
    {
        $st = Database::get()->prepare(
            'SELECT l.*, s.perm AS share_perm,
                    (SELECT COUNT(*) FROM ledger_entries e WHERE e.ledger_id = l.id) AS entry_count
               FROM ledgers l
               LEFT JOIN ledger_shares s ON s.ledger_id = l.id AND s.person_id = ?
              WHERE l.family_id = ? AND (l.owner_id = ? OR s.person_id IS NOT NULL)
              ORDER BY l.id'
        );
        $st->execute([$personId, $familyId, $personId]);
        $out = [];
        foreach ($st->fetchAll() as $r) {
            $r['my_perm'] = (int)$r['owner_id'] === $personId
                ? 'write'
                : (string)($r['share_perm'] ?? 'read');
            $out[] = $r;
        }
        return $out;
    }

    public static function find(int $familyId, int $id, int $personId): ?array
    {
        $st = Database::get()->prepare(
            'SELECT l.*, s.perm AS share_perm FROM ledgers l
               LEFT JOIN ledger_shares s ON s.ledger_id = l.id AND s.person_id = ?
              WHERE l.id = ? AND l.family_id = ? AND (l.owner_id = ? OR s.person_id IS NOT NULL)'
        );
        $st->execute([$personId, $id, $familyId, $personId]);
        $r = $st->fetch();
        if (!$r) {
            return null;
        }
        $r['my_perm'] = (int)$r['owner_id'] === $personId ? 'write' : (string)($r['share_perm'] ?? 'read');
        return $r;
    }

    public static function canWrite(array $ledger): bool
    {
        return ($ledger['my_perm'] ?? '') === 'write';
    }

    /** 账本里的全部账目 */
    public static function entries(int $ledgerId): array
    {
        $st = Database::get()->prepare(
            'SELECT e.*, p.name AS person_name, p.avatar, p.avatar_color,
                    n.nickname AS person_nick
               FROM ledger_entries e
               LEFT JOIN persons p   ON p.id = e.person_id
               LEFT JOIN nicknames n ON n.target_id = e.person_id AND n.viewer_id = ?
              WHERE e.ledger_id = ? ORDER BY e.id'
        );
        $st->execute([0, $ledgerId]);
        return $st->fetchAll();
    }

    /**
     * 这本账的汇总。
     * @return array{asset:int,debt:int,net:int,by_kind:array<string,int>,count:int}
     */
    public static function summary(array $entries): array
    {
        $asset = 0;
        $debt  = 0;
        $byKind = [];
        foreach ($entries as $e) {
            $amt  = (int)($e['amount_cents'] ?? 0);
            $kind = (string)($e['kind'] ?? 'other');
            $isDebt = (self::KINDS[$kind][1] ?? 'asset') === 'debt';
            if ($isDebt) {
                $debt += $amt;
            } else {
                $asset += $amt;
            }
            $byKind[$kind] = ($byKind[$kind] ?? 0) + $amt;
        }
        return [
            'asset'   => $asset,
            'debt'    => $debt,
            'net'     => $asset - $debt,
            'by_kind' => $byKind,
            'count'   => count($entries),
        ];
    }

    // ---------------- 写 ----------------

    /** @return int 新账本 id */
    public static function create(int $familyId, int $ownerId, string $name): int
    {
        $db = Database::get();
        $name = trim($name);
        if ($name === '') {
            $name = '家庭账本';
        }
        $db->prepare('INSERT INTO ledgers (family_id, owner_id, name) VALUES (?,?,?)')
           ->execute([$familyId, $ownerId ?: null, mb_substr($name, 0, 60, 'UTF-8')]);
        return (int)$db->lastInsertId();
    }

    /**
     * 这个家庭至少有**一本我能看到的**账本；没有就建一本并给我共享。
     * @return int 账本 id
     */
    public static function ensureDefault(int $familyId, int $personId): int
    {
        $mine = self::mine($familyId, $personId);
        if ($mine) {
            return (int)$mine[0]['id'];
        }
        $id = self::create($familyId, $personId, '家庭账本');
        return $id;   // 建的人就是 owner，天然能写
    }

    public static function rename(int $familyId, int $id, string $name): void
    {
        Database::get()->prepare('UPDATE ledgers SET name = ? WHERE id = ? AND family_id = ?')
            ->execute([mb_substr(trim($name), 0, 60, 'UTF-8'), $id, $familyId]);
    }

    public static function remove(int $familyId, int $id): void
    {
        // 账目与共享行靠外键 ON DELETE CASCADE 一起走
        Database::get()->prepare('DELETE FROM ledgers WHERE id = ? AND family_id = ?')
            ->execute([$id, $familyId]);
    }

    /** 共享给某人（重复共享 = 改权限） */
    public static function setShare(int $ledgerId, int $personId, string $perm = 'read'): void
    {
        $perm = isset(self::PERM[$perm]) ? $perm : 'read';
        Database::get()->prepare(
            'INSERT INTO ledger_shares (ledger_id, person_id, perm) VALUES (?,?,?)
             ON DUPLICATE KEY UPDATE perm = VALUES(perm)'
        )->execute([$ledgerId, $personId, $perm]);
    }

    public static function unshare(int $ledgerId, int $personId): void
    {
        Database::get()->prepare('DELETE FROM ledger_shares WHERE ledger_id = ? AND person_id = ?')
            ->execute([$ledgerId, $personId]);
    }

    public static function shares(int $ledgerId): array
    {
        $st = Database::get()->prepare(
            'SELECT s.*, p.name, p.avatar, p.avatar_color
               FROM ledger_shares s JOIN persons p ON p.id = s.person_id
              WHERE s.ledger_id = ? ORDER BY s.id'
        );
        $st->execute([$ledgerId]);
        return $st->fetchAll();
    }

    /** @return int 新增账目 id */
    public static function addEntry(int $ledgerId, array $d, int $byId = 0): int
    {
        $db = Database::get();
        $db->prepare(
            'INSERT INTO ledger_entries (ledger_id, kind, title, amount_cents, note, person_id, created_by)
             VALUES (?,?,?,?,?,?,?)'
        )->execute([
            $ledgerId,
            self::kind($d['kind'] ?? ''),
            mb_substr(trim((string)($d['title'] ?? '')), 0, 120, 'UTF-8'),
            self::toCents($d['amount'] ?? ''),
            trim((string)($d['note'] ?? '')) ?: null,
            (int)($d['person_id'] ?? 0) ?: null,
            $byId ?: null,
        ]);
        return (int)$db->lastInsertId();
    }

    public static function updateEntry(int $ledgerId, int $id, array $d): void
    {
        Database::get()->prepare(
            'UPDATE ledger_entries SET kind=?, title=?, amount_cents=?, note=?, person_id=?
              WHERE id=? AND ledger_id=?'
        )->execute([
            self::kind($d['kind'] ?? ''),
            mb_substr(trim((string)($d['title'] ?? '')), 0, 120, 'UTF-8'),
            self::toCents($d['amount'] ?? ''),
            trim((string)($d['note'] ?? '')) ?: null,
            (int)($d['person_id'] ?? 0) ?: null,
            $id, $ledgerId,
        ]);
    }

    public static function removeEntry(int $ledgerId, int $id): void
    {
        Database::get()->prepare('DELETE FROM ledger_entries WHERE id = ? AND ledger_id = ?')
            ->execute([$id, $ledgerId]);
    }

    // ---------------- 钱 ----------------

    /**
     * 「元」→「分」。
     *
     * ⚠️ 不能用 (int)($yuan * 100)：浮点乘法会掉一分（19.99 * 100 = 1998.9999…）。
     *    一律走字符串：拆出整数部与小数部，各自转整数再拼。
     */
    public static function toCents($yuan): int
    {
        $s = trim((string)$yuan);
        $s = str_replace([',', '，', ' '], '', $s);
        if ($s === '') {
            return 0;
        }
        $neg = false;
        if ($s[0] === '-') {
            $neg = true;
            $s = substr($s, 1);
        }
        if (!preg_match('/^(\d*)(?:\.(\d*))?$/', $s, $m)) {
            return 0;
        }
        $intPart = $m[1] !== '' ? $m[1] : '0';
        $dec = $m[2] ?? '';
        $dec = str_pad(substr($dec, 0, 2), 2, '0');    // 超过两位小数直接截断（不做四舍五入到厘）
        $cents = (int)$intPart * 100 + (int)$dec;
        return $neg ? -$cents : $cents;
    }

    /** 「分」→ 显示用的「元」字符串（总是两位小数） */
    public static function amountYuan($cents): string
    {
        $c = (int)$cents;
        $neg = $c < 0;
        $c = abs($c);
        $s = sprintf('%d.%02d', intdiv($c, 100), $c % 100);
        return ($neg ? '-' : '') . $s;
    }

    /** 带千分位、带 ¥ 的显示（列表/汇总用） */
    public static function money($cents): string
    {
        $c = (int)$cents;
        $neg = $c < 0;
        $c = abs($c);
        $s = number_format(intdiv($c, 100)) . '.' . sprintf('%02d', $c % 100);
        return ($neg ? '-' : '') . '¥' . $s;
    }

    public static function kind(string $k): string
    {
        return isset(self::KINDS[$k]) ? $k : 'other';
    }

    public static function kindWord(string $k): string
    {
        return self::KINDS[$k][0] ?? '其它';
    }

    public static function kindIcon(string $k): string
    {
        return self::KINDS[$k][2] ?? '📦';
    }

    public static function isDebt(string $k): bool
    {
        return (self::KINDS[$k][1] ?? 'asset') === 'debt';
    }
}