use anyhow::{Result, Context};
use regex::Regex;
use reqwest::{Client, header::HeaderMap};
use serde::Deserialize;
use std::env;

#[derive(Deserialize)]
struct GitLabIssueResponse {
    iid: u64,
    title: String,
    description: Option<String>,
    web_url: String,
    author: Option<GitLabAuthor>,
    labels: Option<Vec<String>>,
    state: Option<String>,
}

#[derive(Deserialize)]
struct GitLabAuthor {
    username: String,
}

pub async fn fetch_gitlab_issue(url: &str) -> Result<super::IssueContent> {
    let (project_id, number) = parse_gitlab_url(url)?;

    let client = Client::new();
    let token = env::var("GITLAB_TOKEN").ok();

    let mut headers = HeaderMap::new();
    if let Some(ref token) = token {
        headers.insert("PRIVATE-TOKEN", token.parse()?);
    }

    let api_url = env::var("GITLAB_API_URL").unwrap_or_else(|_| "https://gitlab.com/api/v4".to_string());
    let project_encoded = project_id.replace("/", "%2F");
    let issue_url = format!("{}/projects/{}/issues/{}", api_url, project_encoded, number);

    let response = client
        .get(&issue_url)
        .headers(headers)
        .send()
        .await
        .with_context(|| "Failed to fetch GitLab issue")?;

    if !response.status().is_success() {
        anyhow::bail!("Failed to fetch GitLab issue: HTTP {}", response.status());
    }

    let issue: GitLabIssueResponse = response.json().await
        .with_context(|| "Failed to parse GitLab response")?;

    let labels = issue.labels.unwrap_or_default();
    let author = issue.author.map(|a| a.username).unwrap_or_default();

    Ok(super::IssueContent {
        title: issue.title,
        body: issue.description.unwrap_or_default(),
        number: issue.iid,
        url: issue.web_url,
        labels,
        author,
        state: issue.state.unwrap_or_default(),
    })
}

fn parse_gitlab_url(url: &str) -> Result<(String, u64)> {
    let re = regex::Regex::new(r"gitlab\.com/([a-zA-Z0-9._/-]+)/-/?(?:issues|merge_requests)/(\d+)")?;
    let caps = re.captures(url)
        .ok_or_else(|| anyhow::anyhow!("Invalid GitLab URL format: {}", url))?;

    let project_id = caps.get(1)
        .ok_or_else(|| anyhow::anyhow!("Could not extract project ID"))?
        .as_str()
        .to_string();

    let number = caps.get(2)
        .ok_or_else(|| anyhow::anyhow!("Could not extract issue number"))?
        .as_str()
        .parse::<u64>()?;

    Ok((project_id, number))
}