// src/ads.rs
use serde::{Deserialize, Serialize};
use reqwest::header::{HeaderMap, HeaderValue, AUTHORIZATION, CONTENT_TYPE};
use tracing::{info, error};

// 原始 ADS API 返回的数据文档结构
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AdsPaperDoc {
    pub bibcode: String,
    pub title: Option<Vec<String>>,
    pub author: Option<Vec<String>>,
    pub year: Option<String>,
    #[serde(rename = "pub")]
    pub pub_journal: Option<String>,
    pub keyword: Option<Vec<String>>,
    pub abstract_text: Option<String>,
    pub doi: Option<Vec<String>>,
    pub citation_count: Option<i32>,
    pub reference_count: Option<i32>,
    pub reference: Option<Vec<String>>,
    pub citation: Option<Vec<String>>,
    pub identifier: Option<Vec<String>>,
}

#[derive(Debug, Deserialize)]
pub struct AdsResponseDocs {
    pub docs: Vec<AdsPaperDoc>,
}

#[derive(Debug, Deserialize)]
pub struct AdsSearchResponse {
    pub response: AdsResponseDocs,
}

#[derive(Debug, Deserialize)]
pub struct AdsExportResponse {
    pub export: String,
}

// ADS API 服务客户端
#[derive(Clone)]
pub struct AdsClient {
    api_key: String,
    client: reqwest::Client,
}

impl AdsClient {
    pub fn new(api_key: String) -> Self {
        AdsClient {
            api_key,
            client: reqwest::Client::new(),
        }
    }

    // 拼装鉴权 Header
    fn headers(&self) -> HeaderMap {
        let mut headers = HeaderMap::new();
        headers.insert(
            AUTHORIZATION,
            HeaderValue::from_str(&format!("Bearer {}", self.api_key)).unwrap_or_else(|_| HeaderValue::from_static("")),
        );
        headers.insert(CONTENT_TYPE, HeaderValue::from_static("application/json"));
        headers
    }

    // 调用 ADS 检索接口获取文献元数据列表，支持分页与排序
    pub async fn search(&self, query: &str, start: i32, rows: i32, sort: &str) -> anyhow::Result<Vec<AdsPaperDoc>> {
        let url = "https://api.adsabs.harvard.edu/v1/search/query";
        
        let translated = crate::services::query_parser::to_ads_query(query);

        // fl 声明返回字段，包括 reference 和 citation 引用关系数组及 identifier
        let fl = "bibcode,title,author,year,pub,keyword,abstract,doi,citation_count,reference_count,reference,citation,identifier";
        
        let ads_sort = match sort {
            "date_desc" => "date desc",
            "date_asc" => "date asc",
            "citations_desc" => "citation_count desc",
            _ => "score desc",
        };

        info!("正在发送检索请求到 ADS 平台: 原始词='{}', 翻译词='{}', 起始={}, 数量={}, 排序='{}'", query, translated, start, rows, ads_sort);

        let start_str = start.to_string();
        let rows_str = rows.to_string();

        let response = self.client
            .get(url)
            .headers(self.headers())
            .query(&[
                ("q", translated.as_str()),
                ("start", start_str.as_str()),
                ("rows", rows_str.as_str()),
                ("fl", fl),
                ("sort", ads_sort),
            ])
            .send()
            .await?;

        if !response.status().is_success() {
            let status = response.status();
            let err_body = response.text().await.unwrap_or_default();
            error!("ADS 检索请求失败: 状态码={}, 返回错误={}", status, err_body);
            return Err(anyhow::anyhow!("ADS API 接口返回错误码: {}", status));
        }

        let raw_res: RawSearchResponse = response.json().await?;
        let docs = raw_res.response.docs.into_iter().map(|d| {
            AdsPaperDoc {
                bibcode: d.bibcode,
                title: d.title,
                author: d.author,
                year: d.year,
                pub_journal: d.pub_journal,
                keyword: d.keyword,
                abstract_text: d.abstract_field,
                doi: d.doi,
                citation_count: d.citation_count,
                reference_count: d.reference_count,
                reference: d.reference,
                citation: d.citation,
                identifier: d.identifier,
            }
        }).collect();

        Ok(docs)
    }

    // 调用 ADS Export 接口导出 BibTeX 文本内容
    pub async fn export_bibtex(&self, bibcodes: Vec<String>) -> anyhow::Result<String> {
        let url = "https://api.adsabs.harvard.edu/v1/export/bibtex";
        info!("正在向 ADS 请求导出 {} 篇文献的 BibTeX 数据", bibcodes.len());

        let payload = serde_json::json!({
            "bibcode": bibcodes
        });

        let response = self.client
            .post(url)
            .headers(self.headers())
            .json(&payload)
            .send()
            .await?;

        if !response.status().is_success() {
            let status = response.status();
            let err_body = response.text().await.unwrap_or_default();
            error!("ADS 导出 BibTeX 失败: 状态码={}, 返回信息={}", status, err_body);
            return Err(anyhow::anyhow!("ADS 导出接口返回错误码: {}", status));
        }

        let res_data: AdsExportResponse = response.json().await?;
        Ok(res_data.export)
    }

    // 获取某个查询词在 ADS 的匹配文献总量
    pub async fn get_total_count(&self, query: &str) -> anyhow::Result<i32> {
        let url = "https://api.adsabs.harvard.edu/v1/search/query";
        let translated = crate::services::query_parser::to_ads_query(query);

        info!("正在向 ADS 查询匹配的总文献数, 原始词: '{}', 翻译词: '{}'", query, translated);
        let response = self.client
            .get(url)
            .headers(self.headers())
            .query(&[("q", translated.as_str()), ("rows", "0")])
            .send()
            .await?;

        if !response.status().is_success() {
            let status = response.status();
            return Err(anyhow::anyhow!("ADS API 接口返回错误码: {}", status));
        }

        #[derive(Deserialize)]
        struct SimpleResponse {
            response: SimpleDocs,
        }
        #[derive(Deserialize)]
        struct SimpleDocs {
            #[serde(rename = "numFound")]
            num_found: i32,
        }

        let raw: SimpleResponse = response.json().await?;
        Ok(raw.response.num_found)
    }
}

// 内部反序列化辅助结构，防止由于 abstract/pub 关键字冲突导致编译失败
#[derive(Debug, Deserialize)]
struct RawDoc {
    bibcode: String,
    title: Option<Vec<String>>,
    author: Option<Vec<String>>,
    year: Option<String>,
    #[serde(rename = "pub")]
    pub_journal: Option<String>,
    keyword: Option<Vec<String>>,
    #[serde(rename = "abstract")]
    abstract_field: Option<String>,
    doi: Option<Vec<String>>,
    citation_count: Option<i32>,
    reference_count: Option<i32>,
    reference: Option<Vec<String>>,
    citation: Option<Vec<String>>,
    identifier: Option<Vec<String>>,
}

#[derive(Debug, Deserialize)]
struct RawSearchResponse {
    response: RawDocs,
}

#[derive(Debug, Deserialize)]
struct RawDocs {
    docs: Vec<RawDoc>,
}