use crate::state::SessionState;
use ignore::WalkBuilder;
use serde::Serialize;
use std::fs;
use std::path::PathBuf;
use tauri::State;

// -----------------------------------------------------------------------------
// Helper Functions
// -----------------------------------------------------------------------------

/// Helper to get the root path (cloned) without joining
fn get_project_root(state: &State<'_, SessionState>) -> Result<PathBuf, String> {
    state.inner().get_project_root()
}

// -----------------------------------------------------------------------------
// Commands
// -----------------------------------------------------------------------------

#[derive(Serialize, Debug)]
pub struct SearchResult {
    path: String, // Relative path
    matches: usize,
}

/// Searches for files containing the specified query string within the current project.
///
/// This command performs a case-sensitive substring search across all files in the project,
/// respecting `.gitignore` rules by default. The search is executed on a blocking thread
/// to avoid blocking the async runtime.
///
/// # Arguments
///
/// * `query` - The search string to look for in file contents
/// * `state` - The session state containing the project root path
///
/// # Returns
///
/// Returns a `Vec<SearchResult>` containing:
/// - `path`: The relative path of each matching file
/// - `matches`: The number of matches (currently simplified to 1 per file)
///
/// # Errors
///
/// Returns an error if:
/// - No project is currently open
/// - The project root lock cannot be acquired
/// - The search task fails to execute
///
/// # Note
///
/// This is a naive implementation that reads entire files into memory.
/// For production use, consider using streaming/buffered reads or the `grep-searcher` crate.
/// Search files implementation (pure function for testing)
pub async fn search_files_impl(query: String, root: PathBuf) -> Result<Vec<SearchResult>, String> {
    let root_clone = root.clone();

    // Run computationally expensive search on a blocking thread
    let results = tauri::async_runtime::spawn_blocking(move || {
        let mut matches = Vec::new();
        // default to respecting .gitignore
        let walker = WalkBuilder::new(&root_clone).git_ignore(true).build();

        for result in walker {
            match result {
                Ok(entry) => {
                    if !entry.file_type().map(|ft| ft.is_file()).unwrap_or(false) {
                        continue;
                    }

                    let path = entry.path();
                    // Try to read file
                    // Note: This is a naive implementation reading whole files into memory.
                    // For production, we should stream/buffer reads or use grep-searcher.
                    if let Ok(content) = fs::read_to_string(path) {
                        // Simple substring search (case-sensitive)
                        if content.contains(&query) {
                            // Compute relative path for display
                            let relative = path
                                .strip_prefix(&root_clone)
                                .unwrap_or(path)
                                .to_string_lossy()
                                .to_string();

                            matches.push(SearchResult {
                                path: relative,
                                matches: 1, // Simplified count for now
                            });
                        }
                    }
                }
                Err(err) => eprintln!("Error walking dir: {}", err),
            }
        }
        matches
    })
    .await
    .map_err(|e| format!("Search task failed: {}", e))?;

    Ok(results)
}

#[tauri::command]
pub async fn search_files(
    query: String,
    state: State<'_, SessionState>,
) -> Result<Vec<SearchResult>, String> {
    let root = get_project_root(&state)?;
    search_files_impl(query, root).await
}

// -----------------------------------------------------------------------------
// Tests
// -----------------------------------------------------------------------------

#[cfg(test)]
mod tests {
    use super::*;
    use std::fs;
    use std::sync::Mutex;
    use tempfile::TempDir;

    /// Helper to create a test SessionState with a given root path
    fn create_test_state(root: Option<PathBuf>) -> SessionState {
        let (cancel_tx, cancel_rx) = tokio::sync::watch::channel(false);
        SessionState {
            project_root: Mutex::new(root),
            cancel_tx,
            cancel_rx,
        }
    }

    #[tokio::test]
    async fn test_search_files_no_project_open() {
        let state = create_test_state(None);

        let result = state.get_project_root();

        assert!(result.is_err());
        assert_eq!(result.unwrap_err(), "No project is currently open.");
    }

    #[tokio::test]
    async fn test_search_files_finds_matching_file() {
        let temp_dir = TempDir::new().unwrap();
        let test_file = temp_dir.path().join("test.txt");
        fs::write(&test_file, "This is a test file with some content").unwrap();

        let state = create_test_state(Some(temp_dir.path().to_path_buf()));

        let root = state.get_project_root().unwrap();
        let results = search_files_impl("test".to_string(), root).await.unwrap();

        assert_eq!(results.len(), 1);
        assert_eq!(results[0].path, "test.txt");
        assert_eq!(results[0].matches, 1);
    }

    #[tokio::test]
    async fn test_search_files_multiple_matches() {
        let temp_dir = TempDir::new().unwrap();

        // Create multiple files with matching content
        fs::write(temp_dir.path().join("file1.txt"), "hello world").unwrap();
        fs::write(temp_dir.path().join("file2.txt"), "hello again").unwrap();
        fs::write(temp_dir.path().join("file3.txt"), "goodbye").unwrap();

        let state = create_test_state(Some(temp_dir.path().to_path_buf()));

        let root = state.get_project_root().unwrap();
        let results = search_files_impl("hello".to_string(), root).await.unwrap();

        assert_eq!(results.len(), 2);
        let paths: Vec<&str> = results.iter().map(|r| r.path.as_str()).collect();
        assert!(paths.contains(&"file1.txt"));
        assert!(paths.contains(&"file2.txt"));
    }

    #[tokio::test]
    async fn test_search_files_no_matches() {
        let temp_dir = TempDir::new().unwrap();
        fs::write(temp_dir.path().join("test.txt"), "This is some content").unwrap();

        let state = create_test_state(Some(temp_dir.path().to_path_buf()));

        let root = state.get_project_root().unwrap();
        let results = search_files_impl("nonexistent".to_string(), root)
            .await
            .unwrap();

        assert_eq!(results.len(), 0);
    }

    #[tokio::test]
    async fn test_search_files_case_sensitive() {
        let temp_dir = TempDir::new().unwrap();
        fs::write(temp_dir.path().join("test.txt"), "Hello World").unwrap();

        let state = create_test_state(Some(temp_dir.path().to_path_buf()));

        // Search for lowercase - should not match
        let root = state.get_project_root().unwrap();
        let results = search_files_impl("hello".to_string(), root.clone())
            .await
            .unwrap();
        assert_eq!(results.len(), 0);

        // Search for correct case - should match
        let results = search_files_impl("Hello".to_string(), root).await.unwrap();
        assert_eq!(results.len(), 1);
    }

    #[tokio::test]
    async fn test_search_files_nested_directories() {
        let temp_dir = TempDir::new().unwrap();

        // Create nested directory structure
        let nested_dir = temp_dir.path().join("subdir");
        fs::create_dir(&nested_dir).unwrap();

        fs::write(temp_dir.path().join("root.txt"), "match").unwrap();
        fs::write(nested_dir.join("nested.txt"), "match").unwrap();

        let state = create_test_state(Some(temp_dir.path().to_path_buf()));

        let root = state.get_project_root().unwrap();
        let results = search_files_impl("match".to_string(), root).await.unwrap();

        assert_eq!(results.len(), 2);
        let paths: Vec<&str> = results.iter().map(|r| r.path.as_str()).collect();
        assert!(paths.contains(&"root.txt"));
        assert!(paths.contains(&"subdir/nested.txt") || paths.contains(&"subdir\\nested.txt"));
    }

    #[tokio::test]
    async fn test_search_files_respects_gitignore() {
        let temp_dir = TempDir::new().unwrap();

        // Initialize git repo (required for ignore crate to respect .gitignore)
        std::process::Command::new("git")
            .args(["init"])
            .current_dir(temp_dir.path())
            .output()
            .unwrap();

        // Create .gitignore
        fs::write(temp_dir.path().join(".gitignore"), "ignored.txt\n").unwrap();

        // Create files
        fs::write(temp_dir.path().join("included.txt"), "searchterm").unwrap();
        fs::write(temp_dir.path().join("ignored.txt"), "searchterm").unwrap();

        let state = create_test_state(Some(temp_dir.path().to_path_buf()));

        let root = state.get_project_root().unwrap();
        let results = search_files_impl("searchterm".to_string(), root)
            .await
            .unwrap();

        // Should find the non-ignored file, but not the ignored one
        // The gitignore file itself might be included
        let has_included = results.iter().any(|r| r.path == "included.txt");
        let has_ignored = results.iter().any(|r| r.path == "ignored.txt");

        assert!(has_included, "included.txt should be found");
        assert!(
            !has_ignored,
            "ignored.txt should NOT be found (it's in .gitignore)"
        );
    }

    #[tokio::test]
    async fn test_search_files_skips_binary_files() {
        let temp_dir = TempDir::new().unwrap();

        // Create a text file
        fs::write(temp_dir.path().join("text.txt"), "searchable").unwrap();

        // Create a binary file (will fail to read as UTF-8)
        fs::write(temp_dir.path().join("binary.bin"), [0xFF, 0xFE, 0xFD]).unwrap();

        let state = create_test_state(Some(temp_dir.path().to_path_buf()));

        let root = state.get_project_root().unwrap();
        let results = search_files_impl("searchable".to_string(), root)
            .await
            .unwrap();

        // Should only find the text file
        assert_eq!(results.len(), 1);
        assert_eq!(results[0].path, "text.txt");
    }

    #[tokio::test]
    async fn test_search_files_empty_query() {
        let temp_dir = TempDir::new().unwrap();
        fs::write(temp_dir.path().join("test.txt"), "content").unwrap();

        let state = create_test_state(Some(temp_dir.path().to_path_buf()));

        let root = state.get_project_root().unwrap();
        let results = search_files_impl("".to_string(), root).await.unwrap();

        // Empty string is contained in all strings, so should match
        assert_eq!(results.len(), 1);
    }
}