// src/services/batch/meta.rs
use std::sync::Arc;
use tokio::sync::Mutex;
use serde::Serialize;
use tracing::{info, warn, error};
use sqlx::SqlitePool;

use crate::clients::ads::AdsClient;
use crate::clients::arxiv::ArxivClient;
use crate::api::handlers::{convert_ads_doc_to_standard, convert_arxiv_to_standard, save_paper_to_db};

// 批量元数据同步进度状态
#[derive(Debug, Clone, Serialize)]
pub struct MetaSyncStatus {
    pub active: bool,
    pub query: String,
    pub source: String,
    pub synced: i32,
    pub total: i32,
}

impl MetaSyncStatus {
    pub fn new() -> Self {
        MetaSyncStatus {
            active: false,
            query: String::new(),
            source: String::new(),
            synced: 0,
            total: 0,
        }
    }
}

pub struct MetaSync;

impl MetaSync {
    // 预估文献总量
    pub async fn get_total_count(
        query: &str,
        source: &str,
        ads: &AdsClient,
        arxiv: &ArxivClient,
    ) -> anyhow::Result<i32> {
        let mut total = 0;
        if source == "all" || source == "ads" {
            match ads.get_total_count(query).await {
                Ok(count) => {
                    total += count;
                    info!("ADS 预估文献总量: {} 篇", count);
                }
                Err(e) => {
                    warn!("获取 ADS 预估总量失败: {}", e);
                }
            }
        }
        if source == "all" || source == "arxiv" {
            match arxiv.get_total_count(query).await {
                Ok(count) => {
                    total += count;
                    info!("arXiv 预估文献总量: {} 篇", count);
                }
                Err(e) => {
                    warn!("获取 arXiv 预估总量失败: {}", e);
                }
            }
        }
        Ok(total)
    }

    // 启动后台元数据同步异步任务
    pub fn start_harvest(
        db: SqlitePool,
        ads: Arc<AdsClient>,
        arxiv: Arc<ArxivClient>,
        query: String,
        source: String,
        limit: i32,
        status: Arc<Mutex<MetaSyncStatus>>,
    ) {
        let query_clone = query.clone();
        let source_clone = source.clone();

        tokio::spawn(async move {
            info!("启动后台批量元数据同步任务: 查询词='{}', 源='{}', 上限={}", query_clone, source_clone, limit);
            
            // 自动将检索配置存入/更新至 sync_queries 数据库表中进行去重和时间更新
            let _ = sqlx::query(
                "INSERT INTO sync_queries (query, source, limit_count, last_run) \
                 VALUES (?, ?, ?, CURRENT_TIMESTAMP) \
                 ON CONFLICT(query, source, limit_count) DO UPDATE SET last_run=excluded.last_run"
            )
            .bind(&query_clone)
            .bind(&source_clone)
            .bind(limit)
            .execute(&db)
            .await;

            // 1. 并行获取两端预估总量
            let ads_count_fut = {
                let ads = ads.clone();
                let query = query_clone.clone();
                let is_active = source_clone == "all" || source_clone == "ads";
                async move {
                    if is_active {
                        ads.get_total_count(&query).await.unwrap_or(0)
                    } else {
                        0
                    }
                }
            };

            let arxiv_count_fut = {
                let arxiv = arxiv.clone();
                let query = query_clone.clone();
                let is_active = source_clone == "all" || source_clone == "arxiv";
                async move {
                    if is_active {
                        arxiv.get_total_count(&query).await.unwrap_or(0)
                    } else {
                        0
                    }
                }
            };

            let (ads_total, arxiv_total) = tokio::join!(ads_count_fut, arxiv_count_fut);
            let total_count = ads_total + arxiv_total;

            {
                let mut s = status.lock().await;
                s.total = total_count;
            }

            // 计算实际需要元数据同步的总上限，并按比例分配或根据实际匹配量上限控制
            let limit_to_harvest = if limit > 0 { std::cmp::min(limit, total_count) } else { total_count };

            // 共享的 atomic 计数器，以便两端并行同步时独立累加进度
            let synced_counter = Arc::new(std::sync::atomic::AtomicI32::new(0));

            // 2. 执行并行的同步子任务
            let ads_sync_fut = {
                let db = db.clone();
                let ads = ads.clone();
                let query = query_clone.clone();
                let synced_counter = synced_counter.clone();
                let status = status.clone();
                let is_active = source_clone == "all" || source_clone == "ads";
                
                // 如果是 all 模式，各平台按比例分摊 limit 额度，或者直接限制自身的最大可用量
                let ads_limit = if source_clone == "all" {
                    if ads_total == 0 { 0 } else {
                        let ratio = ads_total as f32 / total_count as f32;
                        ((limit_to_harvest as f32) * ratio).round() as i32
                    }
                } else {
                    limit_to_harvest
                };

                async move {
                    if !is_active || ads_limit <= 0 {
                        return;
                    }
                    let mut local_synced = 0;
                    let mut start_offset = 0;
                    while local_synced < ads_limit {
                        let chunk_size = std::cmp::min(2000, ads_limit - local_synced);
                        if chunk_size <= 0 {
                            break;
                        }
                        info!("正在同步 ADS 分批数据: start={}, rows={}", start_offset, chunk_size);
                        match ads.search(&query, start_offset, chunk_size, "relevance").await {
                            Ok(docs) => {
                                if docs.is_empty() {
                                    break;
                                }
                                let count = docs.len() as i32;
                                for doc in docs {
                                    let paper = convert_ads_doc_to_standard(&doc);
                                    let _ = save_paper_to_db(&db, &paper).await;
                                }
                                local_synced += count;
                                start_offset += count;

                                // 累加全局进度并更新状态
                                let current_global = synced_counter.fetch_add(count, std::sync::atomic::Ordering::SeqCst) + count;
                                {
                                    let mut s = status.lock().await;
                                    s.synced = current_global;
                                }
                            }
                            Err(e) => {
                                error!("批量同步 ADS 数据出错: {}", e);
                                break;
                            }
                        }
                    }
                }
            };

            let arxiv_sync_fut = {
                let db = db.clone();
                let arxiv = arxiv.clone();
                let query = query_clone.clone();
                let synced_counter = synced_counter.clone();
                let status = status.clone();
                let is_active = source_clone == "all" || source_clone == "arxiv";

                let arxiv_limit = if source_clone == "all" {
                    if arxiv_total == 0 { 0 } else {
                        let ratio = arxiv_total as f32 / total_count as f32;
                        ((limit_to_harvest as f32) * ratio).round() as i32
                    }
                } else {
                    limit_to_harvest
                };

                async move {
                    if !is_active || arxiv_limit <= 0 {
                        return;
                    }
                    let mut local_synced = 0;
                    let mut start_offset = 0;
                    while local_synced < arxiv_limit {
                        let chunk_size = std::cmp::min(2000, arxiv_limit - local_synced);
                        if chunk_size <= 0 {
                            break;
                        }
                        info!("正在同步 arXiv 分批数据: start={}, max_results={}", start_offset, chunk_size);
                        match arxiv.search(&query, start_offset, chunk_size, "relevance").await {
                            Ok(papers) => {
                                if papers.is_empty() {
                                    break;
                                }
                                let count = papers.len() as i32;
                                for p in papers {
                                    let paper = convert_arxiv_to_standard(&p);
                                    let _ = save_paper_to_db(&db, &paper).await;
                                }
                                local_synced += count;
                                start_offset += count;

                                // 累加全局进度并更新状态
                                let current_global = synced_counter.fetch_add(count, std::sync::atomic::Ordering::SeqCst) + count;
                                {
                                    let mut s = status.lock().await;
                                    s.synced = current_global;
                                }
                            }
                            Err(e) => {
                                error!("批量同步 arXiv 数据出错: {}", e);
                                break;
                            }
                        }

                        // 遵循 arXiv API 3 秒间隔要求
                        tokio::time::sleep(tokio::time::Duration::from_secs(3)).await;
                    }
                }
            };

            // 使用 tokio::join! 并行驱动两端同步任务
            tokio::join!(ads_sync_fut, arxiv_sync_fut);

            // 4. 收尾并重置状态
            let final_synced = synced_counter.load(std::sync::atomic::Ordering::SeqCst);
            {
                let mut s = status.lock().await;
                s.active = false;
                s.synced = final_synced;
                info!("后台批量元数据同步任务已结束。共成功同步 {} 篇文献。", final_synced);
            }
        });
    }
}