use anyhow::{Context, anyhow};
use ias_common::queue::ChannelMessage;
use serde::Deserialize;
use serde_json::{Value, json};

#[derive(Debug, Deserialize)]
struct CallHttpApiArgs {
    endpoint_id: String,
    path_params: Option<Value>,
    query: Option<Value>,
    body: Option<Value>,
    #[allow(dead_code)]
    text: Option<String>,
}

#[derive(Debug, Deserialize)]
struct ApiDocResponse {
    doc: ApiDoc,
}

#[derive(Debug, Deserialize)]
struct ApiDoc {
    group: String,
    method: String,
    path: String,
}

pub async fn call_http_api(channel: &ChannelMessage, arguments: &str) -> String {
    match call_http_api_inner(channel, arguments).await {
        Ok(result) => result,
        Err(error) => format!("工具调用失败: 调用 HTTP API 失败: {error}"),
    }
}

async fn call_http_api_inner(channel: &ChannelMessage, arguments: &str) -> anyhow::Result<String> {
    let args: CallHttpApiArgs =
        serde_json::from_str(arguments).context("解析 call_http_api 参数失败")?;
    let endpoint_id = validate_endpoint_id(args.endpoint_id.trim())?;
    let doc = fetch_api_doc(&endpoint_id).await?;
    let path = fill_path_params(&doc.path, args.path_params.as_ref())?;
    let mut url = reqwest::Url::parse(&format!("{}{}", http_api_base_url(), path))
        .with_context(|| format!("构造 HTTP API 地址失败: {}", doc.path))?;
    append_query(&mut url, args.query.as_ref())?;

    let method = doc.method.trim().to_ascii_uppercase();
    let mut body = args.body.unwrap_or_else(|| json!({}));
    if !body.is_object() {
        return Err(anyhow!("body 必须是对象"));
    }
    if doc.group == "context" {
        body = json_with_identity(channel, body);
    }

    let client = reqwest::Client::new();
    let mut request = match method.as_str() {
        "GET" => client.get(url.clone()),
        "POST" => client.post(url.clone()).json(&body),
        "PATCH" => client.patch(url.clone()).json(&body),
        "DELETE" => client.delete(url.clone()).json(&body),
        other => return Err(anyhow!("不支持的 HTTP 方法: {other}")),
    };
    if doc.group == "context" {
        request = request.header("x-ias-context-token", context_api_key()?);
    }

    let response = request
        .send()
        .await
        .with_context(|| format!("请求 HTTP API 失败: {method} {url}"))?;
    let status = response.status();
    let raw_body = response.text().await.unwrap_or_default();
    if !status.is_success() {
        return Err(anyhow!(
            "接口返回失败: endpoint_id={endpoint_id}, status={status}, body={raw_body}"
        ));
    }

    let value: Value = serde_json::from_str(&raw_body).context("解析 HTTP API 响应失败")?;
    let pretty = serde_json::to_string_pretty(&value).unwrap_or_else(|_| value.to_string());
    Ok(format!(
        "HTTP API 调用成功：{endpoint_id}\n{} {}\n响应：\n{}",
        method,
        path,
        trim_for_result(&pretty, 8_000)
    ))
}

async fn fetch_api_doc(endpoint_id: &str) -> anyhow::Result<ApiDoc> {
    let url = reqwest::Url::parse(&format!(
        "{}/v1/api-docs/{endpoint_id}",
        http_api_base_url()
    ))
    .context("构造 API 文档详情地址失败")?;
    let response = reqwest::Client::new()
        .get(url.clone())
        .send()
        .await
        .with_context(|| format!("请求 API 文档详情失败: {url}"))?;
    let status = response.status();
    let body = response.text().await.unwrap_or_default();
    if !status.is_success() {
        return Err(anyhow!(
            "API 文档不存在或不可用: status={status}, body={body}"
        ));
    }

    let response: ApiDocResponse = serde_json::from_str(&body).context("解析 API 文档详情失败")?;
    Ok(response.doc)
}

fn fill_path_params(path: &str, path_params: Option<&Value>) -> anyhow::Result<String> {
    let mut path = path.to_string();
    let params = path_params.and_then(Value::as_object);
    while let Some(start) = path.find('{') {
        let Some(end_offset) = path[start..].find('}') else {
            return Err(anyhow!("API 文档 path 占位符格式错误: {path}"));
        };
        let end = start + end_offset;
        let name = &path[start + 1..end];
        let value = params
            .and_then(|params| params.get(name))
            .ok_or_else(|| anyhow!("缺少 path_params.{name}"))?;
        let encoded = percent_encode_path_segment(&json_scalar_to_string(value)?);
        path.replace_range(start..=end, &encoded);
    }
    Ok(path)
}

fn append_query(url: &mut reqwest::Url, query: Option<&Value>) -> anyhow::Result<()> {
    let Some(query) = query else {
        return Ok(());
    };
    let Some(query) = query.as_object() else {
        return Err(anyhow!("query 必须是对象"));
    };

    let mut pairs = url.query_pairs_mut();
    for (key, value) in query {
        if value.is_null() {
            continue;
        }
        pairs.append_pair(key, &json_scalar_to_string(value)?);
    }
    Ok(())
}

fn json_with_identity(channel: &ChannelMessage, mut payload: Value) -> Value {
    let Value::Object(map) = &mut payload else {
        return payload;
    };
    map.insert("channel".to_string(), json!(channel.channel));
    map.insert("account_id".to_string(), json!(channel.account_id));
    map.insert("from_user_id".to_string(), json!(channel.from_user_id));
    map.insert("context".to_string(), json!(channel.context));
    map.insert("group_id".to_string(), json!(channel.group_id));
    payload
}

fn json_scalar_to_string(value: &Value) -> anyhow::Result<String> {
    match value {
        Value::String(value) => Ok(value.trim().to_string()),
        Value::Number(value) => Ok(value.to_string()),
        Value::Bool(value) => Ok(value.to_string()),
        Value::Null => Err(anyhow!("参数值不能为 null")),
        Value::Array(_) | Value::Object(_) => Err(anyhow!("参数值只能是字符串、数字或布尔值")),
    }
}

fn validate_endpoint_id(value: &str) -> anyhow::Result<String> {
    if value.is_empty() {
        return Err(anyhow!("endpoint_id 不能为空"));
    }
    if value
        .bytes()
        .all(|byte| byte.is_ascii_alphanumeric() || byte == b'.' || byte == b'-' || byte == b'_')
    {
        Ok(value.to_string())
    } else {
        Err(anyhow!(
            "endpoint_id 只能包含字母、数字、点、下划线或连字符"
        ))
    }
}

fn http_api_base_url() -> String {
    std::env::var("IA_HTTP_API_BASE_URL")
        .or_else(|_| std::env::var("IA_WEB_INTERNAL_URL"))
        .or_else(|_| std::env::var("HOST").map(|host| format!("http://{host}")))
        .unwrap_or_else(|_| "http://127.0.0.1:9003".to_string())
        .trim()
        .trim_end_matches('/')
        .replace("0.0.0.0", "127.0.0.1")
}

fn context_api_key() -> anyhow::Result<String> {
    std::env::var("IA_CONTEXT_API_KEY")
        .or_else(|_| std::env::var("IA_CONTEXT_TOKEN"))
        .or_else(|_| std::env::var("ROUTER_API_KEY"))
        .map(|value| value.trim().to_string())
        .ok()
        .filter(|value| !value.is_empty())
        .ok_or_else(|| anyhow!("未配置 IA_CONTEXT_API_KEY/IA_CONTEXT_TOKEN/ROUTER_API_KEY"))
}

fn trim_for_result(value: &str, max_chars: usize) -> String {
    let mut text = value.chars().take(max_chars).collect::<String>();
    if value.chars().count() > max_chars {
        text.push_str("...");
    }
    text
}

fn percent_encode_path_segment(value: &str) -> String {
    let mut encoded = String::new();
    for byte in value.bytes() {
        if byte.is_ascii_alphanumeric() || matches!(byte, b'-' | b'_' | b'.' | b'~') {
            encoded.push(byte as char);
        } else {
            encoded.push_str(&format!("%{byte:02X}"));
        }
    }
    encoded
}