use std::{collections::HashMap, sync::Arc};

use async_trait::async_trait;
use regex::Regex;
use reqwest::Client;
use serde::{Deserialize, Serialize};

use super::traits::PlatformClient;
use crate::{
  error::{PakkerError, Result},
  model::{Project, ProjectFile, ProjectSide, ProjectType, ReleaseType},
  utils::generate_pakku_id,
};

const GITHUB_API_BASE: &str = "https://api.github.com";

pub struct GitHubPlatform {
  client: Client,
  token:  Option<String>,
}

impl GitHubPlatform {
  pub fn with_client(client: Arc<Client>, token: Option<String>) -> Self {
    Self {
      client: (*client).clone(),
      token,
    }
  }

  fn get_headers(&self) -> Result<reqwest::header::HeaderMap> {
    let mut headers = reqwest::header::HeaderMap::new();
    headers.insert(
      reqwest::header::USER_AGENT,
      reqwest::header::HeaderValue::from_static("Pakker"),
    );

    if let Some(token) = &self.token {
      headers.insert(
        reqwest::header::AUTHORIZATION,
        reqwest::header::HeaderValue::from_str(&format!("Bearer {token}"))
          .map_err(|_| {
            PakkerError::ConfigError("Invalid GitHub token".to_string())
          })?,
      );
    }

    Ok(headers)
  }

  fn parse_repo_identifier(identifier: &str) -> Result<(String, String)> {
    // Expected formats:
    // - "owner/repo"
    // - "github:owner/repo"
    // - "https://github.com/owner/repo"

    let identifier = identifier
      .trim_start_matches("github:")
      .trim_start_matches("https://github.com/")
      .trim_start_matches("http://github.com/")
      .trim_end_matches(".git");

    let parts: Vec<&str> = identifier.split('/').collect();
    if parts.len() >= 2 {
      Ok((parts[0].to_string(), parts[1].to_string()))
    } else {
      Err(PakkerError::InvalidInput(format!(
        "Invalid GitHub repository identifier: {identifier}"
      )))
    }
  }

  fn convert_release(
    &self,
    owner: &str,
    repo: &str,
    release: GitHubRelease,
  ) -> Project {
    let pakku_id = generate_pakku_id();
    let mut project =
      Project::new(pakku_id, ProjectType::Mod, ProjectSide::Both);

    let repo_full = format!("{owner}/{repo}");
    project.add_platform(
      "github".to_string(),
      repo_full.clone(),
      repo_full,
      release.name.unwrap_or_else(|| repo.to_string()),
    );

    project
  }
}

// Helper functions for extracting metadata from GitHub releases
fn extract_mc_versions(tag: &str, asset_name: &str) -> Vec<String> {
  let re = Regex::new(r"(?:^|[^\d.])(\d+\.\d+(?:\.\d+)?)(?:[^\d]|$)").unwrap();
  let mut versions = Vec::new();

  log::debug!("Extracting MC versions from tag='{tag}', asset='{asset_name}'");

  for text in &[tag, asset_name] {
    for cap in re.captures_iter(text) {
      if let Some(version) = cap.get(1) {
        let v = version.as_str().to_string();
        if !versions.contains(&v) {
          log::debug!("  Found MC version: {v}");
          versions.push(v);
        }
      }
    }
  }

  log::debug!("Extracted MC versions: {versions:?}");
  versions
}

fn extract_loaders(tag: &str, asset_name: &str) -> Vec<String> {
  let mut loaders = Vec::new();
  let text = format!("{} {}", tag.to_lowercase(), asset_name.to_lowercase());

  log::debug!("Extracting loaders from: '{text}'");

  if text.contains("fabric") {
    log::debug!("  Found loader: fabric");
    loaders.push("fabric".to_string());
  }
  if text.contains("forge") && !text.contains("neoforge") {
    log::debug!("  Found loader: forge");
    loaders.push("forge".to_string());
  }
  if text.contains("neoforge") {
    log::debug!("  Found loader: neoforge");
    loaders.push("neoforge".to_string());
  }
  if text.contains("quilt") {
    log::debug!("  Found loader: quilt");
    loaders.push("quilt".to_string());
  }

  log::debug!("Extracted loaders: {loaders:?}");
  loaders
}

fn detect_project_type(asset_name: &str, repo_name: &str) -> ProjectType {
  let name_lower = asset_name.to_lowercase();
  let repo_lower = repo_name.to_lowercase();

  // Check for resourcepack indicators
  if name_lower.contains("resourcepack")
    || name_lower.contains("resource-pack")
    || name_lower.contains("texture")
    || repo_lower.contains("resourcepack")
    || repo_lower.contains("texture")
  {
    return ProjectType::ResourcePack;
  }

  // Check for datapack indicators
  if name_lower.contains("datapack")
    || name_lower.contains("data-pack")
    || repo_lower.contains("datapack")
  {
    return ProjectType::DataPack;
  }

  // Check for shader indicators
  if name_lower.contains("shader") || repo_lower.contains("shader") {
    return ProjectType::Shader;
  }

  // Check for world/save indicators
  if name_lower.contains("world")
    || name_lower.contains("save")
    || repo_lower.contains("world")
  {
    return ProjectType::World;
  }

  // Default to mod for .jar files
  ProjectType::Mod
}

impl GitHubPlatform {
  fn convert_asset(
    &self,
    asset: GitHubAsset,
    release: &GitHubRelease,
    repo_id: &str,
    repo_name: &str,
  ) -> ProjectFile {
    let hashes = HashMap::new();

    // Extract MC versions and loaders from tag and asset name
    let mc_versions = extract_mc_versions(&release.tag_name, &asset.name);
    let loaders = extract_loaders(&release.tag_name, &asset.name);

    // Detect project type from asset name and repo
    let file_type = match detect_project_type(&asset.name, repo_name) {
      ProjectType::Mod => "mod",
      ProjectType::ResourcePack => "resourcepack",
      ProjectType::DataPack => "datapack",
      ProjectType::Shader => "shader",
      ProjectType::World => "world",
    };

    ProjectFile {
      file_type: file_type.to_string(),
      file_name: asset.name.clone(),
      mc_versions,
      loaders,
      release_type: if release.prerelease {
        ReleaseType::Beta
      } else {
        ReleaseType::Release
      },
      url: asset.browser_download_url.clone(),
      id: asset.id.to_string(),
      parent_id: repo_id.to_string(),
      hashes,
      required_dependencies: vec![],
      size: asset.size,
      date_published: release.published_at.clone().unwrap_or_default(),
    }
  }

  async fn get_latest_release(
    &self,
    owner: &str,
    repo: &str,
  ) -> Result<GitHubRelease> {
    let url = format!("{GITHUB_API_BASE}/repos/{owner}/{repo}/releases/latest");

    let response = self
      .client
      .get(&url)
      .headers(self.get_headers()?)
      .send()
      .await?;

    if !response.status().is_success() {
      return Err(PakkerError::ProjectNotFound(format!("{owner}/{repo}")));
    }

    let release: GitHubRelease = response.json().await?;
    Ok(release)
  }

  async fn get_all_releases(
    &self,
    owner: &str,
    repo: &str,
  ) -> Result<Vec<GitHubRelease>> {
    let url = format!("{GITHUB_API_BASE}/repos/{owner}/{repo}/releases");

    let response = self
      .client
      .get(&url)
      .headers(self.get_headers()?)
      .send()
      .await?;

    if !response.status().is_success() {
      return Err(PakkerError::ProjectNotFound(format!("{owner}/{repo}")));
    }

    let releases: Vec<GitHubRelease> = response.json().await?;
    Ok(releases)
  }
}

#[async_trait]
impl PlatformClient for GitHubPlatform {
  async fn request_project(
    &self,
    identifier: &str,
    _mc_versions: &[String],
    _loaders: &[String],
  ) -> Result<Project> {
    let (owner, repo) = Self::parse_repo_identifier(identifier)?;
    let release = self.get_latest_release(&owner, &repo).await?;
    Ok(self.convert_release(&owner, &repo, release))
  }

  async fn request_project_files(
    &self,
    project_id: &str,
    _mc_versions: &[String],
    _loaders: &[String],
  ) -> Result<Vec<ProjectFile>> {
    let (owner, repo) = Self::parse_repo_identifier(project_id)?;
    let releases = self.get_all_releases(&owner, &repo).await?;

    let mut files = Vec::new();

    for release in releases {
      for asset in &release.assets {
        // Filter for .jar files (mods) or .zip files (modpacks)
        if asset.name.ends_with(".jar") || asset.name.ends_with(".zip") {
          let file =
            self.convert_asset(asset.clone(), &release, project_id, &repo);
          files.push(file);
        }
      }
    }

    Ok(files)
  }

  async fn request_project_with_files(
    &self,
    identifier: &str,
    _mc_versions: &[String],
    _loaders: &[String],
  ) -> Result<Project> {
    let mut project = self
      .request_project(identifier, _mc_versions, _loaders)
      .await?;

    let project_id = project
      .get_platform_id("github")
      .ok_or_else(|| {
        PakkerError::InternalError("Missing github ID".to_string())
      })?
      .clone();

    let files = self
      .request_project_files(&project_id, _mc_versions, _loaders)
      .await?;

    project.files = files;

    Ok(project)
  }

  async fn lookup_by_hash(&self, hash: &str) -> Result<Option<Project>> {
    log::debug!("GitHub lookup_by_hash: searching for hash={hash}");

    // GitHub Code Search API: search for files containing the hash
    // Note: This is rate-limited (10 req/min without auth, 30 req/min with
    // auth)
    let url = format!("{GITHUB_API_BASE}/search/code?q={hash}+in:file");
    log::debug!("GitHub search URL: {url}");

    let response = match self
      .client
      .get(&url)
      .headers(self.get_headers()?)
      .send()
      .await
    {
      Ok(resp) => {
        log::debug!("GitHub search response status: {}", resp.status());
        resp
      },
      Err(e) => {
        log::warn!("GitHub hash lookup failed: {e}");
        return Ok(None);
      },
    };

    // Handle rate limiting gracefully
    if response.status().as_u16() == 403 {
      log::warn!("GitHub API rate limit exceeded for hash lookup");
      return Ok(None);
    }

    if !response.status().is_success() {
      log::debug!(
        "GitHub search returned non-success status: {}",
        response.status()
      );
      return Ok(None);
    }

    let search_result: GitHubCodeSearchResult = match response.json().await {
      Ok(result) => result,
      Err(e) => {
        log::warn!("Failed to parse GitHub search result: {e}");
        return Ok(None);
      },
    };

    log::debug!("GitHub search found {} items", search_result.items.len());

    // If we found matches, try to extract repo info from first result
    if let Some(item) = search_result.items.first() {
      let repo_full = item.repository.full_name.clone();
      log::info!("GitHub hash lookup found match in repo: {repo_full}");

      // Try to get the latest release for this repo
      match self.request_project(&repo_full, &[], &[]).await {
        Ok(project) => {
          log::info!("GitHub hash lookup succeeded for {repo_full}");
          Ok(Some(project))
        },
        Err(e) => {
          log::warn!("Failed to fetch project for {repo_full}: {e}");
          Ok(None)
        },
      }
    } else {
      log::debug!("GitHub hash lookup found no matches");
      Ok(None)
    }
  }
}

// GitHub API models
#[derive(Debug, Clone, Deserialize, Serialize)]
struct GitHubRelease {
  id:           u64,
  tag_name:     String,
  name:         Option<String>,
  prerelease:   bool,
  published_at: Option<String>,
  assets:       Vec<GitHubAsset>,
}

#[derive(Debug, Clone, Deserialize, Serialize)]
struct GitHubAsset {
  id:                   u64,
  name:                 String,
  browser_download_url: String,
  size:                 u64,
}

#[derive(Debug, Deserialize)]
struct GitHubCodeSearchResult {
  items: Vec<GitHubCodeSearchItem>,
}

#[derive(Debug, Deserialize)]
struct GitHubCodeSearchItem {
  repository: GitHubRepository,
}

#[derive(Debug, Deserialize)]
struct GitHubRepository {
  full_name: String,
}

#[cfg(test)]
mod tests {
  use super::*;

  #[test]
  fn test_parse_repo_identifier() {
    let cases = vec![
      ("owner/repo", ("owner", "repo")),
      ("github:owner/repo", ("owner", "repo")),
      ("https://github.com/owner/repo", ("owner", "repo")),
      ("https://github.com/owner/repo.git", ("owner", "repo")),
    ];

    for (input, (expected_owner, expected_repo)) in cases {
      let (owner, repo) = GitHubPlatform::parse_repo_identifier(input).unwrap();
      assert_eq!(owner, expected_owner);
      assert_eq!(repo, expected_repo);
    }
  }

  #[test]
  fn test_parse_repo_identifier_invalid() {
    let result = GitHubPlatform::parse_repo_identifier("invalid");
    assert!(result.is_err());
  }

  #[test]
  fn test_extract_mc_versions() {
    let cases = vec![
      ("1.20.4-forge-1.0.0", "", vec!["1.20.4", "1.0.0"]),
      ("fabric-1.21-1.0.0", "", vec!["1.21"]),
      ("mc1.20.4", "", vec!["1.20.4"]),
      ("1.20.1-1.20.2", "", vec!["1.20.1"]),
      ("mymod-1.0.0", "", vec!["1.0.0"]),
      ("mc1.20.4-v1.0.0", "", vec!["1.20.4", "1.0.0"]),
      ("v1.0.0", "mymod-1.20.4.jar", vec!["1.0.0", "1.20.4"]),
      ("1.20.1-47.1.0", "", vec!["1.20.1"]),
      ("v0.5.1+1.20.1", "", vec!["0.5.1"]),
      ("1.20.4-1.0.0+fabric", "", vec!["1.20.4"]),
      ("mc1.19.2-v2.1.3", "", vec!["1.19.2", "2.1.3"]),
      ("1.20-Snapshot", "", vec!["1.20"]),
      ("v3.0.0-beta.2+mc1.20.4", "", vec!["3.0.0", "1.20.4"]),
      ("1.16.5-1.0", "", vec!["1.16.5"]),
      ("forge-1.20.1-47.2.0", "", vec!["1.20.1"]),
      ("1.20.2-neoforge-20.2.59", "", vec!["1.20.2", "20.2.59"]),
      ("release-1.20.1", "", vec!["1.20.1"]),
      ("1.19.4_v2.5.0", "", vec!["1.19.4", "2.5.0"]),
      ("MC1.18.2-v1.0.0", "", vec!["1.18.2", "1.0.0"]),
      ("1.20.1-forge-v1.2.3", "", vec!["1.20.1", "1.2.3"]),
      ("Minecraft_1.19.2-v0.8.1", "", vec!["1.19.2", "0.8.1"]),
      ("build-1.20.4-2.1.0", "", vec!["1.20.4"]),
      ("1.20.x-1.5.0", "", vec!["1.20", "1.5.0"]),
      ("1.12.2-14.23.5.2859", "", vec!["1.12.2"]),
    ];

    for (tag, asset, expected) in cases {
      let result = extract_mc_versions(tag, asset);
      assert_eq!(
        result, expected,
        "Failed for tag: {}, asset: {}",
        tag, asset
      );
    }
  }

  #[test]
  fn test_extract_loaders() {
    let cases = vec![
      ("1.20.4-forge-1.0.0", "", vec!["forge"]),
      ("fabric-1.21-1.0.0", "", vec!["fabric"]),
      ("1.20.1-neoforge", "", vec!["neoforge"]),
      ("quilt-1.20.4", "", vec!["quilt"]),
      ("mymod-1.0.0", "", vec![]),
      ("1.20.4-forge-fabric", "", vec!["fabric", "forge"]), /* Alphabetical
                                                             * order */
      ("v1.0.0", "mymod-fabric-1.20.4.jar", vec!["fabric"]),
      // Real-world patterns
      ("1.20.1-forge-47.1.0", "", vec!["forge"]),
      ("fabric-api-0.92.0+1.20.4", "", vec!["fabric"]),
      ("1.19.2-neoforge-20.2.59", "", vec!["neoforge"]),
      ("quilt-loader-0.23.0", "", vec!["quilt"]),
      ("1.20.4-Fabric-1.0.0", "", vec!["fabric"]), // Capitalized
      ("forge-1.20.1", "", vec!["forge"]),
      ("v1.0.0-fabric", "", vec!["fabric"]),
      ("1.18.2-forge+fabric", "", vec!["fabric", "forge"]), // Both loaders
      ("NeoForge-1.20.2", "", vec!["neoforge"]),            /* Capitalized
                                                             * NeoForge */
      ("1.12.2-forge-14.23.5.2859", "", vec!["forge"]), // Old format
    ];

    for (tag, asset, expected) in cases {
      let result = extract_loaders(tag, asset);
      assert_eq!(
        result, expected,
        "Failed for tag: {}, asset: {}",
        tag, asset
      );
    }
  }

  #[test]
  fn test_detect_project_type() {
    let cases = vec![
      ("mymod.jar", "mymod", crate::model::ProjectType::Mod),
      (
        "texture-pack.zip",
        "texture",
        crate::model::ProjectType::ResourcePack,
      ),
      (
        "resourcepack.zip",
        "resources",
        crate::model::ProjectType::ResourcePack,
      ),
      (
        "datapack.zip",
        "data-stuff",
        crate::model::ProjectType::DataPack,
      ),
      (
        "shader.zip",
        "awesome-shaders",
        crate::model::ProjectType::Shader,
      ),
      ("world.zip", "my-world", crate::model::ProjectType::World),
      ("save.zip", "survival", crate::model::ProjectType::World),
      ("unknown.zip", "stuff", crate::model::ProjectType::Mod),
    ];

    for (filename, repo_name, expected) in cases {
      let result = detect_project_type(filename, repo_name);
      assert_eq!(
        result, expected,
        "Failed for filename: {}, repo: {}",
        filename, repo_name
      );
    }
  }
}