<?php

namespace App\Business;

use App\Models\Auth\User;
use App\Models\Business\SystemizationTodo;
use Illuminate\Support\Carbon;
use Illuminate\Support\Facades\DB;
use RuntimeException;
use Throwable;

class SystemizationTodoAuditLogger
{
    public const TABLE = 'business_systemization_todo_audit_logs';

    public const HISTORY_LIMIT = 500;

    public const ACTION_LABELS = [
        'create' => '新增',
        'update' => '修改',
        'delete' => '删除',
        'import' => '导入',
    ];

    public const FIELD_LABELS = [
        'category' => '类型',
        'section' => '内容',
        'title' => '待办事项',
        'owner' => '总负责人',
        'assignee' => '责任人',
        'start_date' => '开始时间',
        'start_note' => '开始时间备注',
        'due_date' => '完成时间',
        'due_note' => '完成时间备注',
        'status' => '状态',
        'completed_at' => '完成日期',
        'progress' => '完成情况',
        'notes' => '备注',
        'attachment_count' => '完成截图',
        'sort_order' => '排序位置',
    ];

    /**
     * @return array<string, mixed>
     */
    public function snapshot(SystemizationTodo $todo, bool $withAttachments = false): array
    {
        $snapshot = [
            'id' => (int) $todo->id,
            'category' => (string) ($todo->category ?? ''),
            'section' => (string) ($todo->section ?? ''),
            'title' => (string) ($todo->title ?? ''),
            'owner' => (string) ($todo->owner ?? ''),
            'assignee' => (string) ($todo->assignee ?? ''),
            'start_date' => $todo->start_date?->format('Y-m-d') ?? '',
            'start_note' => (string) ($todo->start_note ?? ''),
            'due_date' => $todo->due_date?->format('Y-m-d') ?? '',
            'due_note' => (string) ($todo->due_note ?? ''),
            'status' => $todo->statusLabel(),
            'completed_at' => $todo->completed_at?->format('Y-m-d') ?? '',
            'progress' => (string) ($todo->progress ?? ''),
            'notes' => (string) ($todo->notes ?? ''),
            'sort_order' => (int) $todo->sort_order,
            'source_key' => (string) ($todo->source_key ?? ''),
        ];

        if ($withAttachments) {
            $snapshot['attachment_count'] = (int) $todo->attachments()->count();
        }

        return $snapshot;
    }

    public function record(
        string $action,
        int $companyId,
        ?int $todoId,
        ?array $before,
        ?array $after,
        ?int $userId = null,
        ?string $actorName = null,
        array $meta = [],
    ): void {
        $this->recordMany([[
            'company_id' => $companyId,
            'todo_id' => $todoId,
            'action' => $action,
            'before' => $before,
            'after' => $after,
            'user_id' => $userId,
            'actor_name' => $actorName,
            'meta' => $meta,
        ]]);
    }

    /**
     * @param  array<int, array{
     *     company_id:int,
     *     todo_id:?int,
     *     action:string,
     *     before:?array,
     *     after:?array,
     *     user_id:?int,
     *     actor_name?:?string,
     *     meta?:array
     * }>  $events
     */
    public function recordMany(array $events): void
    {
        if ($events === []) {
            return;
        }
        if (! $this->tableReady()) {
            throw new RuntimeException('系统化待办操作记录表尚未就绪，请先完成数据库迁移。');
        }

        $now = $this->platformNow();
        $actorNames = [];
        $rows = [];
        foreach ($events as $event) {
            $action = (string) ($event['action'] ?? '');
            if (! array_key_exists($action, self::ACTION_LABELS)) {
                throw new RuntimeException('不支持的待办操作记录类型。');
            }

            $userId = isset($event['user_id']) ? (int) $event['user_id'] : null;
            $actorName = trim((string) ($event['actor_name'] ?? ''));
            if ($actorName === '' && $userId !== null) {
                if (! array_key_exists($userId, $actorNames)) {
                    $actorNames[$userId] = (string) (User::query()->whereKey($userId)->value('name') ?? '');
                }
                $actorName = $actorNames[$userId];
            }

            $meta = is_array($event['meta'] ?? null) ? $event['meta'] : [];
            $rows[] = [
                'company_id' => max(1, (int) ($event['company_id'] ?? 1)),
                'todo_id' => isset($event['todo_id']) ? (int) $event['todo_id'] : null,
                'action' => $action,
                'before_json' => $this->json($event['before'] ?? null),
                'after_json' => $this->json($event['after'] ?? null),
                'actor_user_id' => $userId,
                'actor_name' => mb_substr($actorName, 0, 191),
                'extra_json' => $meta === [] ? null : $this->json($meta),
                'at' => $now->toDateTimeString(),
                'created_at' => $now->toDateTimeString(),
                'updated_at' => $now->toDateTimeString(),
            ];
        }

        DB::table(self::TABLE)->insert($rows);
        $companyIds = array_values(array_unique(array_column($rows, 'company_id')));
        foreach ($companyIds as $companyId) {
            $maxId = (int) DB::table(self::TABLE)
                ->where('company_id', $companyId)
                ->max('id');
            if ($maxId > self::HISTORY_LIMIT) {
                DB::table(self::TABLE)
                    ->where('company_id', $companyId)
                    ->where('id', '<=', $maxId - self::HISTORY_LIMIT)
                    ->delete();
            }
        }
    }

    /**
     * @return array<int, array<string, mixed>>
     */
    public function history(
        int $companyId,
        int $limit = self::HISTORY_LIMIT,
        ?string $from = null,
    ): array
    {
        if (! $this->tableReady()) {
            return [];
        }

        return DB::table(self::TABLE)
            ->where('company_id', $companyId)
            ->when($from !== null && $from !== '', fn ($query) => $query->where('at', '>=', $from))
            ->orderByDesc('id')
            ->limit(max(1, min($limit, self::HISTORY_LIMIT)))
            ->get()
            ->map(fn (object $row): array => $this->serializeEvent($row))
            ->all();
    }

    public function platformNow(): Carbon
    {
        $timezone = trim((string) config('app.platform_timezone', ''));
        if ($timezone === '') {
            $timezone = (string) config('app.timezone', 'UTC');
        }

        try {
            return Carbon::now($timezone);
        } catch (Throwable) {
            return Carbon::now((string) config('app.timezone', 'UTC'));
        }
    }

    /**
     * @return array<string, mixed>
     */
    private function serializeEvent(object $row): array
    {
        $before = $row->before_json ? json_decode((string) $row->before_json, true) : null;
        $after = $row->after_json ? json_decode((string) $row->after_json, true) : null;
        $before = is_array($before) ? $before : null;
        $after = is_array($after) ? $after : null;
        $meta = $row->extra_json ? json_decode((string) $row->extra_json, true) : [];
        $meta = is_array($meta) ? $meta : [];
        $source = $after ?? $before ?? [];

        return [
            'id' => (int) $row->id,
            'at' => (string) $row->at,
            'action' => (string) $row->action,
            'action_label' => self::ACTION_LABELS[(string) $row->action] ?? (string) $row->action,
            'todo_id' => $row->todo_id === null ? null : (int) $row->todo_id,
            'category' => (string) ($source['category'] ?? ''),
            'section' => (string) ($source['section'] ?? ''),
            'title' => (string) ($source['title'] ?? ''),
            'actor' => (string) ($row->actor_name ?? ''),
            'before' => $before,
            'after' => $after,
            'meta' => $meta,
            'changes' => $this->changes($before, $after),
        ];
    }

    /**
     * @return array<int, string>
     */
    private function changes(?array $before, ?array $after): array
    {
        if ($after === null && $before !== null) {
            return ['删除前：' . $this->itemLabel($before)];
        }
        if ($before === null && $after !== null) {
            return ['新增：' . $this->itemLabel($after)];
        }
        if ($before === null && $after === null) {
            return ['—'];
        }

        $changes = [];
        foreach (self::FIELD_LABELS as $field => $label) {
            $old = $this->displayValue($field, $before[$field] ?? '');
            $new = $this->displayValue($field, $after[$field] ?? '');
            if ($old !== $new) {
                $changes[] = $label . '：' . ($old !== '' ? $old : '空')
                    . ' → ' . ($new !== '' ? $new : '空');
            }
        }

        return $changes === [] ? ['内容无变化'] : $changes;
    }

    private function itemLabel(array $row): string
    {
        $parts = array_values(array_filter([
            trim((string) ($row['category'] ?? '')),
            trim((string) ($row['section'] ?? '')),
            trim((string) ($row['title'] ?? '')),
        ], static fn (string $value): bool => $value !== ''));

        return $parts === [] ? '未命名待办' : implode(' · ', $parts);
    }

    private function displayValue(string $field, mixed $value): string
    {
        if ($field === 'attachment_count') {
            return max(0, (int) $value) . ' 张';
        }

        return trim(str_replace(["\r\n", "\r"], "\n", (string) ($value ?? '')));
    }

    private function json(mixed $value): ?string
    {
        if ($value === null) {
            return null;
        }

        $json = json_encode($value, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
        if ($json === false) {
            throw new RuntimeException('待办操作记录序列化失败。');
        }

        return $json;
    }

    private function tableReady(): bool
    {
        try {
            return DB::getSchemaBuilder()->hasTable(self::TABLE);
        } catch (Throwable) {
            return false;
        }
    }
}