<?php
declare(strict_types=1);

namespace app\note\service;

use app\note\model\NoteAiSummary;
use app\note\model\NoteItem;

/**
 * note 模块 AI 总结服务
 *
 * 当前先提供规则版总结，保证接口可用。
 * 后续如需接入大模型，可在本服务内部替换实现，不影响控制器接口。
 */
class AiService
{
    /**
     * 生成或刷新总结
     *
     * @param NoteItem $note
     * @param string $summaryType
     * @param bool $forceRefresh
     * @return array
     */
    public function createSummary(NoteItem $note, string $summaryType = 'brief', bool $forceRefresh = false): array
    {
        $summaryType = in_array($summaryType, ['brief', 'outline', 'todo'], true) ? $summaryType : 'brief';
        $existing = NoteAiSummary::findLatestByNoteId((int) $note->id);

        if ($existing && !$forceRefresh && $existing->status === 'success') {
            return $this->formatSummary($existing);
        }

        $sourceText = trim((string) $note->content);
        if ($sourceText === '') {
            $sourceText = trim((string) $note->transcript_text);
        }
        if ($sourceText === '') {
            throw new \Exception('笔记内容为空，无法生成总结', 400);
        }

        $generated = $this->generateSummaryPayload($sourceText, $summaryType);
        $now = time();

        $summary = $existing ?: new NoteAiSummary();
        if (!$existing) {
            $summary->note_id = (int) $note->id;
            $summary->created_at = $now;
        }

        $summary->summary_type = $summaryType;
        $summary->summary_text = $generated['summary_text'];
        $summary->todo_list = json_encode($generated['todo_list'], JSON_UNESCAPED_UNICODE);
        $summary->keywords = json_encode($generated['keywords'], JSON_UNESCAPED_UNICODE);
        $summary->status = 'success';
        $summary->error_message = '';
        $summary->updated_at = $now;
        $summary->save();

        $note->summary_status = 'success';
        $note->updated_at = $now;
        $note->save();

        return $this->formatSummary($summary);
    }

    /**
     * 读取总结
     *
     * @param int $noteId
     * @return array
     * @throws \Exception
     */
    public function getSummary(int $noteId): array
    {
        $summary = NoteAiSummary::findLatestByNoteId($noteId);
        if (!$summary) {
            throw new \Exception('该笔记暂无总结结果', 404);
        }

        return $this->formatSummary($summary);
    }

    /**
     * 生成规则版总结
     *
     * @param string $text
     * @param string $summaryType
     * @return array
     */
    private function generateSummaryPayload(string $text, string $summaryType): array
    {
        $sentences = $this->splitSentences($text);
        $summarySentences = array_slice($sentences, 0, $summaryType === 'outline' ? 5 : 3);
        $summaryText = implode("\n", array_map(function ($item, $index) use ($summaryType) {
            if ($summaryType === 'outline') {
                return sprintf('%d. %s', $index + 1, $item);
            }
            return $item;
        }, $summarySentences, array_keys($summarySentences)));

        $todoList = $this->extractTodoList($text);
        $keywords = $this->extractKeywords($text);

        if ($summaryType === 'todo' && !empty($todoList)) {
            $summaryText = "待办事项：\n" . implode("\n", array_map(function ($item, $index) {
                return sprintf('%d. %s', $index + 1, $item);
            }, $todoList, array_keys($todoList)));
        }

        return [
            'summary_text' => $summaryText !== '' ? $summaryText : mb_substr($text, 0, 200),
            'todo_list' => $todoList,
            'keywords' => $keywords,
        ];
    }

    /**
     * 切分句子
     *
     * @param string $text
     * @return array
     */
    private function splitSentences(string $text): array
    {
        $normalized = preg_replace('/\s+/', ' ', trim($text));
        $parts = preg_split('/[。！？!?；;\n\r]+/u', (string) $normalized);
        $parts = array_values(array_filter(array_map('trim', $parts), function ($item) {
            return $item !== '';
        }));

        return empty($parts) ? [mb_substr($normalized, 0, 200)] : $parts;
    }

    /**
     * 提取待办
     *
     * @param string $text
     * @return array
     */
    private function extractTodoList(string $text): array
    {
        $lines = preg_split('/[\n\r]+/u', $text);
        $todoList = [];

        foreach ($lines as $line) {
            $line = trim($line);
            if ($line === '') {
                continue;
            }
            if (preg_match('/^(待办|todo|todo:|TODO|TODO:|需要|安排|跟进|完成|处理)/u', $line)) {
                $todoList[] = $line;
            }
        }

        if (!empty($todoList)) {
            return array_slice(array_values(array_unique($todoList)), 0, 10);
        }

        $sentences = $this->splitSentences($text);
        $fallback = [];
        foreach ($sentences as $sentence) {
            if (preg_match('/(需要|安排|跟进|完成|处理|确认|整理|联系)/u', $sentence)) {
                $fallback[] = $sentence;
            }
        }

        return array_slice(array_values(array_unique($fallback)), 0, 10);
    }

    /**
     * 提取关键词
     *
     * @param string $text
     * @return array
     */
    private function extractKeywords(string $text): array
    {
        preg_match_all('/[\x{4e00}-\x{9fa5}A-Za-z0-9]{2,20}/u', $text, $matches);
        $words = $matches[0] ?? [];
        $stopWords = ['我们', '你们', '他们', '这个', '那个', '然后', '以及', '因为', '所以', '可以', '进行', '一个', '没有', '已经', '需要', '今天', '目前', '如果', '就是'];
        $countMap = [];

        foreach ($words as $word) {
            if (in_array($word, $stopWords, true)) {
                continue;
            }
            $countMap[$word] = ($countMap[$word] ?? 0) + 1;
        }

        arsort($countMap);
        return array_slice(array_keys($countMap), 0, 10);
    }

    /**
     * 格式化总结结果
     *
     * @param NoteAiSummary $summary
     * @return array
     */
    private function formatSummary(NoteAiSummary $summary): array
    {
        return [
            'summary_id' => (int) $summary->id,
            'note_id' => (int) $summary->note_id,
            'summary_type' => (string) $summary->summary_type,
            'summary_text' => (string) $summary->summary_text,
            'todo_list' => $this->decodeJsonList((string) $summary->todo_list),
            'keywords' => $this->decodeJsonList((string) $summary->keywords),
            'status' => (string) $summary->status,
            'error_message' => (string) $summary->error_message,
            'created_at' => (int) $summary->created_at,
            'updated_at' => (int) $summary->updated_at,
        ];
    }

    /**
     * 解析 JSON 列表
     *
     * @param string $value
     * @return array
     */
    private function decodeJsonList(string $value): array
    {
        $decoded = json_decode($value, true);
        return is_array($decoded) ? $decoded : [];
    }
}