use reqwest::Client;
use serde::{Deserialize, Serialize};
use std::fs;
use std::io::Write;
use std::path::{Path, PathBuf};
use std::process::Command;
use tauri::Emitter;

use crate::extraction::Extractor;

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

#[derive(Debug, Serialize, Deserialize, Clone)]
pub struct AppRelease {
  pub tag_name: String,
  pub name: String,
  pub body: String,
  pub published_at: String,
  pub prerelease: bool,
  pub assets: Vec<AppReleaseAsset>,
}

#[derive(Debug, Serialize, Deserialize, Clone)]
pub struct AppUpdateInfo {
  pub current_version: String,
  pub new_version: String,
  pub release_notes: String,
  pub download_url: String,
  pub is_nightly: bool,
  pub published_at: String,
}

pub struct AppAutoUpdater {
  client: Client,
}

impl AppAutoUpdater {
  pub fn new() -> Self {
    Self {
      client: Client::new(),
    }
  }

  /// Check if running a nightly build based on environment variable
  pub fn is_nightly_build() -> bool {
    // If STABLE_RELEASE env var is set at compile time, it's a stable build
    if option_env!("STABLE_RELEASE").is_some() {
      return false;
    }

    // Also check if the current version starts with "nightly-"
    let current_version = Self::get_current_version();
    if current_version.starts_with("nightly-") {
      return true;
    }

    // If STABLE_RELEASE is not set and version doesn't start with "nightly-",
    // it's still considered a nightly build (dev builds, main branch builds, etc.)
    true
  }

  /// Get current app version from build-time injection
  pub fn get_current_version() -> String {
    // Use build-time injected version instead of CARGO_PKG_VERSION
    env!("BUILD_VERSION").to_string()
  }

  /// Check for app updates
  pub async fn check_for_updates(
    &self,
  ) -> Result<Option<AppUpdateInfo>, Box<dyn std::error::Error + Send + Sync>> {
    let current_version = Self::get_current_version();
    let is_nightly = Self::is_nightly_build();

    println!("=== App Update Check ===");
    println!("Current version: {current_version}");
    println!("Is nightly build: {is_nightly}");
    println!("STABLE_RELEASE env: {:?}", option_env!("STABLE_RELEASE"));

    let releases = self.fetch_app_releases().await?;
    println!("Fetched {} releases from GitHub", releases.len());

    // Filter releases based on build type
    let filtered_releases: Vec<&AppRelease> = if is_nightly {
      // For nightly builds, look for nightly releases
      let nightly_releases: Vec<&AppRelease> = releases
        .iter()
        .filter(|release| release.tag_name.starts_with("nightly-"))
        .collect();
      println!("Found {} nightly releases", nightly_releases.len());
      nightly_releases
    } else {
      // For stable builds, look for stable releases (semver format)
      let stable_releases: Vec<&AppRelease> = releases
        .iter()
        .filter(|release| {
          release.tag_name.starts_with('v') && !release.tag_name.starts_with("nightly-")
        })
        .collect();
      println!("Found {} stable releases", stable_releases.len());
      stable_releases
    };

    if filtered_releases.is_empty() {
      println!("No releases found for build type (nightly: {is_nightly})");
      return Ok(None);
    }

    // Get the latest release
    let latest_release = filtered_releases[0];
    println!(
      "Latest release: {} ({})",
      latest_release.tag_name, latest_release.name
    );

    // Check if we need to update
    if self.should_update(&current_version, &latest_release.tag_name, is_nightly) {
      println!("Update available!");

      // Find the appropriate asset for current platform
      if let Some(download_url) = self.get_download_url_for_platform(&latest_release.assets) {
        let update_info = AppUpdateInfo {
          current_version,
          new_version: latest_release.tag_name.clone(),
          release_notes: latest_release.body.clone(),
          download_url,
          is_nightly,
          published_at: latest_release.published_at.clone(),
        };

        println!(
          "Update info prepared: {} -> {}",
          update_info.current_version, update_info.new_version
        );
        return Ok(Some(update_info));
      } else {
        println!("No suitable download asset found for current platform");
      }
    } else {
      println!("No update needed");
    }

    Ok(None)
  }

  /// Fetch app releases from GitHub
  async fn fetch_app_releases(
    &self,
  ) -> Result<Vec<AppRelease>, Box<dyn std::error::Error + Send + Sync>> {
    let url = "https://api.github.com/repos/zhom/donutbrowser/releases";
    let response = self
      .client
      .get(url)
      .header("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36")
      .send()
      .await?;

    if !response.status().is_success() {
      return Err(format!("GitHub API request failed: {}", response.status()).into());
    }

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

  /// Determine if an update should be performed
  fn should_update(&self, current_version: &str, new_version: &str, is_nightly: bool) -> bool {
    if current_version.starts_with("dev-") {
      return false;
    }

    println!(
      "Comparing versions: current={current_version}, new={new_version}, is_nightly={is_nightly}"
    );

    if is_nightly {
      // For nightly builds, always update if there's a newer nightly
      if let (Some(current_hash), Some(new_hash)) = (
        current_version.strip_prefix("nightly-"),
        new_version.strip_prefix("nightly-"),
      ) {
        // Different commit hashes mean we should update
        let should_update = new_hash != current_hash;
        println!("Nightly comparison: current_hash={current_hash}, new_hash={new_hash}, should_update={should_update}");
        return should_update;
      }

      // If current version doesn't have nightly prefix but we're in nightly mode,
      // this could be a dev build or stable build upgrading to nightly
      if !current_version.starts_with("nightly-") {
        println!("Upgrading from non-nightly to nightly: {new_version}");
        return true;
      }
    } else {
      // For stable builds, use semantic versioning comparison
      let should_update = self.is_version_newer(new_version, current_version);
      println!("Stable comparison: {new_version} > {current_version} = {should_update}");
      return should_update;
    }

    false
  }

  /// Compare semantic versions (returns true if version1 > version2)
  fn is_version_newer(&self, version1: &str, version2: &str) -> bool {
    let v1 = self.parse_semver(version1);
    let v2 = self.parse_semver(version2);
    v1 > v2
  }

  /// Parse semantic version string into comparable tuple
  fn parse_semver(&self, version: &str) -> (u32, u32, u32) {
    let clean_version = version.trim_start_matches('v');
    let parts: Vec<&str> = clean_version.split('.').collect();

    let major = parts.first().and_then(|s| s.parse().ok()).unwrap_or(0);
    let minor = parts.get(1).and_then(|s| s.parse().ok()).unwrap_or(0);
    let patch = parts.get(2).and_then(|s| s.parse().ok()).unwrap_or(0);

    (major, minor, patch)
  }

  /// Get the appropriate download URL for the current platform
  fn get_download_url_for_platform(&self, assets: &[AppReleaseAsset]) -> Option<String> {
    // Priority 1: Get architecture-specific binary for backward compatibility
    let arch = if cfg!(target_arch = "aarch64") {
      "aarch64"
    } else if cfg!(target_arch = "x86_64") {
      "x64"
    } else {
      "unknown"
    };

    println!("Falling back to architecture-specific search for: {arch}");

    // Look for exact architecture match in DMG
    for asset in assets {
      if asset.name.contains(".dmg")
        && (asset.name.contains(&format!("_{arch}.dmg"))
          || asset.name.contains(&format!("-{arch}.dmg"))
          || asset.name.contains(&format!("_{arch}_"))
          || asset.name.contains(&format!("-{arch}-")))
      {
        println!("Found exact architecture match: {}", asset.name);
        return Some(asset.browser_download_url.clone());
      }
    }

    // Look for x86_64 variations if we're looking for x64
    if arch == "x64" {
      for asset in assets {
        if asset.name.contains(".dmg")
          && (asset.name.contains("x86_64") || asset.name.contains("x86-64"))
        {
          println!("Found x86_64 variant: {}", asset.name);
          return Some(asset.browser_download_url.clone());
        }
      }
    }

    // Look for arm64 variations if we're looking for aarch64
    if arch == "aarch64" {
      for asset in assets {
        if asset.name.contains(".dmg")
          && (asset.name.contains("arm64") || asset.name.contains("aarch64"))
        {
          println!("Found arm64 variant: {}", asset.name);
          return Some(asset.browser_download_url.clone());
        }
      }
    }

    // Priority 2: Fallback to any macOS DMG
    for asset in assets {
      if asset.name.contains(".dmg")
        && (asset.name.to_lowercase().contains("macos")
          || asset.name.to_lowercase().contains("darwin")
          || !asset.name.contains(".app.tar.gz"))
      {
        // Exclude app.tar.gz files
        println!("Found fallback DMG: {}", asset.name);
        return Some(asset.browser_download_url.clone());
      }
    }

    println!("No suitable asset found for platform");
    None
  }

  /// Download and install app update
  pub async fn download_and_install_update(
    &self,
    app_handle: &tauri::AppHandle,
    update_info: &AppUpdateInfo,
  ) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
    // Create temporary directory for download
    let temp_dir = std::env::temp_dir().join("donut_app_update");
    fs::create_dir_all(&temp_dir)?;

    // Extract filename from URL
    let filename = update_info
      .download_url
      .split('/')
      .next_back()
      .unwrap_or("update.dmg")
      .to_string();

    // Emit download start event
    let _ = app_handle.emit("app-update-progress", "Downloading update...");

    // Download the update
    let download_path = self
      .download_update(&update_info.download_url, &temp_dir, &filename)
      .await?;

    // Emit extraction start event
    let _ = app_handle.emit("app-update-progress", "Preparing update...");

    // Extract the update
    let extracted_app_path = self.extract_update(&download_path, &temp_dir).await?;

    // Emit installation start event
    let _ = app_handle.emit("app-update-progress", "Installing update...");

    // Install the update (overwrite current app)
    self.install_update(&extracted_app_path).await?;

    // Clean up temporary files
    let _ = fs::remove_dir_all(&temp_dir);

    // Emit completion event
    let _ = app_handle.emit("app-update-progress", "Update completed. Restarting...");

    // Restart the application
    self.restart_application().await?;

    Ok(())
  }

  /// Download the update file
  async fn download_update(
    &self,
    download_url: &str,
    dest_dir: &Path,
    filename: &str,
  ) -> Result<PathBuf, Box<dyn std::error::Error + Send + Sync>> {
    let file_path = dest_dir.join(filename);

    let response = self
      .client
      .get(download_url)
      .header("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36")
      .send()
      .await?;

    if !response.status().is_success() {
      return Err(format!("Download failed with status: {}", response.status()).into());
    }

    let mut file = fs::File::create(&file_path)?;
    let mut stream = response.bytes_stream();

    use futures_util::StreamExt;
    while let Some(chunk) = stream.next().await {
      let chunk = chunk?;
      file.write_all(&chunk)?;
    }

    Ok(file_path)
  }

  /// Extract the update using the extraction module
  async fn extract_update(
    &self,
    archive_path: &Path,
    dest_dir: &Path,
  ) -> Result<PathBuf, Box<dyn std::error::Error + Send + Sync>> {
    let extractor = Extractor::new();

    let extension = archive_path
      .extension()
      .and_then(|ext| ext.to_str())
      .unwrap_or("");

    match extension {
      "dmg" => {
        #[cfg(target_os = "macos")]
        {
          extractor.extract_dmg(archive_path, dest_dir).await
        }
        #[cfg(not(target_os = "macos"))]
        {
          Err("DMG extraction is only supported on macOS".into())
        }
      }
      "zip" => extractor.extract_zip(archive_path, dest_dir).await,
      _ => Err(format!("Unsupported archive format: {extension}").into()),
    }
  }

  /// Install the update by replacing the current app
  async fn install_update(
    &self,
    new_app_path: &Path,
  ) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
    // Get the current application bundle path
    let current_app_path = self.get_current_app_path()?;

    // Create a backup of the current app
    let backup_path = current_app_path.with_extension("app.backup");
    if backup_path.exists() {
      fs::remove_dir_all(&backup_path)?;
    }

    // Move current app to backup
    fs::rename(&current_app_path, &backup_path)?;

    // Move new app to current location
    fs::rename(new_app_path, &current_app_path)?;

    // Remove quarantine attributes from the new app
    let _ = Command::new("xattr")
      .args([
        "-dr",
        "com.apple.quarantine",
        current_app_path.to_str().unwrap(),
      ])
      .output();

    let _ = Command::new("xattr")
      .args(["-cr", current_app_path.to_str().unwrap()])
      .output();

    // Clean up backup after successful installation
    let _ = fs::remove_dir_all(&backup_path);

    Ok(())
  }

  /// Get the current application bundle path
  fn get_current_app_path(&self) -> Result<PathBuf, Box<dyn std::error::Error + Send + Sync>> {
    // Get the current executable path
    let exe_path = std::env::current_exe()?;

    // Navigate up to find the .app bundle
    let mut current = exe_path.as_path();
    while let Some(parent) = current.parent() {
      if parent.extension().is_some_and(|ext| ext == "app") {
        return Ok(parent.to_path_buf());
      }
      current = parent;
    }

    Err("Could not find application bundle".into())
  }

  /// Restart the application
  async fn restart_application(&self) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
    let app_path = self.get_current_app_path()?;
    let current_pid = std::process::id();

    // Create a temporary restart script
    let temp_dir = std::env::temp_dir();
    let script_path = temp_dir.join("donut_restart.sh");

    // Create the restart script content
    let script_content = format!(
      r#"#!/bin/bash
# Wait for the current process to exit
while kill -0 {} 2>/dev/null; do
  sleep 0.5
done

# Wait a bit more to ensure clean exit
sleep 1

# Start the new application
open "{}"

# Clean up this script
rm "{}"
"#,
      current_pid,
      app_path.to_str().unwrap(),
      script_path.to_str().unwrap()
    );

    // Write the script to file
    fs::write(&script_path, script_content)?;

    // Make the script executable
    let _ = Command::new("chmod")
      .args(["+x", script_path.to_str().unwrap()])
      .output();

    // Execute the restart script in the background
    let mut cmd = Command::new("bash");
    cmd.arg(script_path.to_str().unwrap());

    // Detach the process completely
    #[cfg(unix)]
    {
      use std::os::unix::process::CommandExt;
      cmd.process_group(0);
    }

    let _child = cmd.spawn()?;

    // Give the script a moment to start
    tokio::time::sleep(tokio::time::Duration::from_millis(500)).await;

    // Exit the current process
    std::process::exit(0);
  }
}

// Tauri commands

#[tauri::command]
pub async fn check_for_app_updates() -> Result<Option<AppUpdateInfo>, String> {
  let updater = AppAutoUpdater::new();
  updater
    .check_for_updates()
    .await
    .map_err(|e| format!("Failed to check for app updates: {e}"))
}

#[tauri::command]
pub async fn download_and_install_app_update(
  app_handle: tauri::AppHandle,
  update_info: AppUpdateInfo,
) -> Result<(), String> {
  let updater = AppAutoUpdater::new();
  updater
    .download_and_install_update(&app_handle, &update_info)
    .await
    .map_err(|e| format!("Failed to install app update: {e}"))
}

#[tauri::command]
pub async fn check_for_app_updates_manual() -> Result<Option<AppUpdateInfo>, String> {
  println!("Manual app update check triggered");
  let updater = AppAutoUpdater::new();
  updater
    .check_for_updates()
    .await
    .map_err(|e| format!("Failed to check for app updates: {e}"))
}

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

  #[test]
  fn test_is_nightly_build() {
    // This will depend on whether STABLE_RELEASE is set during test compilation
    let is_nightly = AppAutoUpdater::is_nightly_build();
    println!("Is nightly build: {is_nightly}");

    // The result should be true for test builds since STABLE_RELEASE is not set
    // unless the test is run in a stable release environment
    assert!(is_nightly || option_env!("STABLE_RELEASE").is_some());
  }

  #[test]
  fn test_version_comparison() {
    let updater = AppAutoUpdater::new();

    // Test semantic version comparison
    assert!(updater.is_version_newer("v1.1.0", "v1.0.0"));
    assert!(updater.is_version_newer("v2.0.0", "v1.9.9"));
    assert!(updater.is_version_newer("v1.0.1", "v1.0.0"));
    assert!(!updater.is_version_newer("v1.0.0", "v1.0.0"));
    assert!(!updater.is_version_newer("v1.0.0", "v1.0.1"));
  }

  #[test]
  fn test_parse_semver() {
    let updater = AppAutoUpdater::new();

    assert_eq!(updater.parse_semver("v1.2.3"), (1, 2, 3));
    assert_eq!(updater.parse_semver("1.2.3"), (1, 2, 3));
    assert_eq!(updater.parse_semver("v2.0.0"), (2, 0, 0));
    assert_eq!(updater.parse_semver("0.1.0"), (0, 1, 0));
  }

  #[test]
  fn test_should_update_stable() {
    let updater = AppAutoUpdater::new();

    // Stable version updates
    assert!(updater.should_update("v1.0.0", "v1.1.0", false));
    assert!(updater.should_update("v1.0.0", "v2.0.0", false));
    assert!(!updater.should_update("v1.1.0", "v1.0.0", false));
    assert!(!updater.should_update("v1.0.0", "v1.0.0", false));
  }

  #[test]
  fn test_should_update_nightly() {
    let updater = AppAutoUpdater::new();

    // Nightly version updates
    assert!(updater.should_update("nightly-abc123", "nightly-def456", true));
    assert!(!updater.should_update("nightly-abc123", "nightly-abc123", true));

    // Upgrade from stable to nightly
    assert!(updater.should_update("v1.0.0", "nightly-abc123", true));

    // Don't upgrade dev, ever
    assert!(!updater.should_update("dev-0.1.0", "nightly-xyz987", false));
    assert!(!updater.should_update("dev-0.1.0", "nightly-xyz987", true));
    assert!(!updater.should_update("dev-0.1.0", "v1.2.3", false));
  }

  #[test]
  fn test_should_update_edge_cases() {
    let updater = AppAutoUpdater::new();

    // Test with different nightly formats
    assert!(updater.should_update("nightly-abc123", "nightly-def456", true));
    assert!(!updater.should_update("nightly-abc123", "nightly-abc123", true));

    // Test stable version edge cases
    assert!(updater.should_update("v0.9.9", "v1.0.0", false));
    assert!(!updater.should_update("v1.0.0", "v0.9.9", false));
    assert!(!updater.should_update("v1.0.0", "v1.0.0", false));

    // Test version without 'v' prefix
    assert!(updater.should_update("0.9.9", "v1.0.0", false));
    assert!(updater.should_update("v0.9.9", "1.0.0", false));
  }

  #[test]
  fn test_get_download_url_for_platform() {
    let updater = AppAutoUpdater::new();

    let assets = vec![
      AppReleaseAsset {
        name: "Donut.Browser_0.1.0_x64.dmg".to_string(),
        browser_download_url: "https://example.com/x64.dmg".to_string(),
        size: 12345,
      },
      AppReleaseAsset {
        name: "Donut.Browser_0.1.0_aarch64.dmg".to_string(),
        browser_download_url: "https://example.com/aarch64.dmg".to_string(),
        size: 12345,
      },
    ];

    let url = updater.get_download_url_for_platform(&assets);
    assert!(url.is_some());

    // Test with generic macOS DMG (no architecture specified)
    let generic_assets = vec![AppReleaseAsset {
      name: "Donut.Browser_0.1.0_macos.dmg".to_string(),
      browser_download_url: "https://example.com/macos.dmg".to_string(),
      size: 12345,
    }];

    let generic_url = updater.get_download_url_for_platform(&generic_assets);
    assert!(generic_url.is_some());
    assert_eq!(generic_url.unwrap(), "https://example.com/macos.dmg");

    // Test architecture-specific DMG
    let arch_specific_assets = vec![
      AppReleaseAsset {
        name: "Donut.Browser_0.1.0_x64.dmg".to_string(),
        browser_download_url: "https://example.com/x64.dmg".to_string(),
        size: 12345,
      },
      AppReleaseAsset {
        name: "Donut.Browser_0.1.0_aarch64.dmg".to_string(),
        browser_download_url: "https://example.com/aarch64.dmg".to_string(),
        size: 12345,
      },
    ];

    let arch_url = updater.get_download_url_for_platform(&arch_specific_assets);
    assert!(arch_url.is_some());
    // The exact URL depends on the target architecture, but should be one of the available ones
    let arch_url = arch_url.unwrap();
    assert!(arch_url.contains(".dmg"));
  }

  #[test]
  fn test_extract_update_uses_extractor() {
    // This test verifies that the extract_update method properly uses the Extractor
    // We can't run the actual extraction in unit tests without real DMG files,
    // but we can verify the method signature and basic logic
    let updater = AppAutoUpdater::new();

    // Test that unsupported formats would be rejected
    let temp_dir = std::env::temp_dir();
    let unsupported_file = temp_dir.join("test.rar");

    // Create a mock runtime to test the logic
    let rt = tokio::runtime::Runtime::new().unwrap();

    // This would fail because .rar is not supported, which proves
    // our method is using the Extractor logic
    let result = rt.block_on(async { updater.extract_update(&unsupported_file, &temp_dir).await });

    // Should fail with unsupported format error
    assert!(result.is_err());
    let error_msg = result.unwrap_err().to_string();
    assert!(error_msg.contains("Unsupported archive format: rar"));
  }
}