use anyhow::Result;
use futures_util::StreamExt;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::fs;
use std::io::Write;
use std::path::PathBuf;
use std::sync::Mutex;
use tauri::{App, AppHandle, Emitter, Manager};

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ModelInfo {
    pub id: String,
    pub name: String,
    pub description: String,
    pub filename: String,
    pub url: Option<String>,
    pub size_mb: u64,
    pub is_downloaded: bool,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DownloadProgress {
    pub model_id: String,
    pub downloaded: u64,
    pub total: u64,
    pub percentage: f64,
}

pub struct ModelManager {
    app_handle: AppHandle,
    models_dir: PathBuf,
    available_models: Mutex<HashMap<String, ModelInfo>>,
}

impl ModelManager {
    pub fn new(app: &App) -> Result<Self> {
        let app_handle = app.app_handle().clone();

        // Create models directory in app data
        let models_dir = app
            .path()
            .app_data_dir()
            .map_err(|e| anyhow::anyhow!("Failed to get app data dir: {}", e))?
            .join("models");

        if !models_dir.exists() {
            fs::create_dir_all(&models_dir)?;
        }

        let mut available_models = HashMap::new();

        available_models.insert(
            "small".to_string(),
            ModelInfo {
                id: "small".to_string(),
                name: "Whisper Small".to_string(),
                description: "Fast and efficient, great for most use cases".to_string(),
                filename: "ggml-small.bin".to_string(),
                url: Some("https://blob.handy.computer/ggml-small.bin".to_string()),
                size_mb: 244,
                is_downloaded: false,
            },
        );

        // Add downloadable models
        available_models.insert(
            "medium".to_string(),
            ModelInfo {
                id: "medium".to_string(),
                name: "Whisper Medium".to_string(),
                description: "Good accuracy, medium speed".to_string(),
                filename: "ggml-medium-q5_0.bin".to_string(),
                url: Some("https://blob.handy.computer/ggml-medium-q5_0.bin".to_string()),
                size_mb: 539, // Approximate size
                is_downloaded: false,
            },
        );

        available_models.insert(
            "turbo".to_string(),
            ModelInfo {
                id: "turbo".to_string(),
                name: "Whisper Turbo".to_string(),
                description: "Good accuracy, medium speed".to_string(),
                filename: "ggml-large-v3-turbo-q5_0.bin".to_string(),
                url: Some("https://blob.handy.computer/ggml-large-v3-turbo-q5_0.bin".to_string()),
                size_mb: 574, // Approximate size
                is_downloaded: false,
            },
        );

        available_models.insert(
            "large".to_string(),
            ModelInfo {
                id: "large".to_string(),
                name: "Whisper Large".to_string(),
                description: "Highest accuracy, but slow.".to_string(),
                filename: "ggml-large-v3-q5_0.bin".to_string(),
                url: Some("https://blob.handy.computer/ggml-large-v3-q5_0.bin".to_string()),
                size_mb: 1080, // Approximate size
                is_downloaded: false,
            },
        );

        let manager = Self {
            app_handle,
            models_dir,
            available_models: Mutex::new(available_models),
        };

        // Migrate any bundled models to user directory
        manager.migrate_bundled_models()?;

        // Check which models are already downloaded
        manager.update_download_status()?;

        Ok(manager)
    }

    pub fn get_available_models(&self) -> Vec<ModelInfo> {
        let models = self.available_models.lock().unwrap();
        models.values().cloned().collect()
    }

    pub fn get_model_info(&self, model_id: &str) -> Option<ModelInfo> {
        let models = self.available_models.lock().unwrap();
        models.get(model_id).cloned()
    }

    fn migrate_bundled_models(&self) -> Result<()> {
        // Check for bundled models and copy them to user directory
        let bundled_models = ["ggml-small.bin"]; // Add other bundled models here if any

        for filename in &bundled_models {
            let bundled_path = self.app_handle.path().resolve(
                &format!("resources/models/{}", filename),
                tauri::path::BaseDirectory::Resource,
            );

            if let Ok(bundled_path) = bundled_path {
                if bundled_path.exists() {
                    let user_path = self.models_dir.join(filename);

                    // Only copy if user doesn't already have the model
                    if !user_path.exists() {
                        println!("Migrating bundled model {} to user directory", filename);
                        fs::copy(&bundled_path, &user_path)?;
                        println!("Successfully migrated {}", filename);
                    }
                }
            }
        }

        Ok(())
    }

    fn update_download_status(&self) -> Result<()> {
        let mut models = self.available_models.lock().unwrap();

        for model in models.values_mut() {
            let model_path = self.models_dir.join(&model.filename);
            model.is_downloaded = model_path.exists();
        }

        Ok(())
    }

    pub async fn download_model(&self, model_id: &str) -> Result<()> {
        let model_info = {
            let models = self.available_models.lock().unwrap();
            models.get(model_id).cloned()
        };

        let model_info =
            model_info.ok_or_else(|| anyhow::anyhow!("Model not found: {}", model_id))?;

        let url = model_info
            .url
            .ok_or_else(|| anyhow::anyhow!("No download URL for model"))?;
        let model_path = self.models_dir.join(&model_info.filename);

        // Don't download if downloaded version already exists
        if model_path.exists() {
            // Update status and return
            self.update_download_status()?;
            return Ok(());
        }

        println!("Downloading model {} from {}", model_id, url);

        // Create HTTP client
        let client = reqwest::Client::new();
        let response = client.get(&url).send().await?;

        if !response.status().is_success() {
            return Err(anyhow::anyhow!(
                "Failed to download model: HTTP {}",
                response.status()
            ));
        }

        let total_size = response.content_length().unwrap_or(0);
        let mut downloaded = 0u64;
        let mut stream = response.bytes_stream();

        // Create the file
        let mut file = std::fs::File::create(&model_path)?;

        // Download with progress
        while let Some(chunk) = stream.next().await {
            let chunk = chunk?;
            file.write_all(&chunk)?;
            downloaded += chunk.len() as u64;

            let percentage = if total_size > 0 {
                (downloaded as f64 / total_size as f64) * 100.0
            } else {
                0.0
            };

            // Emit progress event
            let progress = DownloadProgress {
                model_id: model_id.to_string(),
                downloaded,
                total: total_size,
                percentage,
            };

            let _ = self.app_handle.emit("model-download-progress", &progress);
        }

        file.flush()?;

        // Update download status
        self.update_download_status()?;

        // Emit completion event
        let _ = self.app_handle.emit("model-download-complete", model_id);

        println!(
            "Successfully downloaded model {} to {:?}",
            model_id, model_path
        );
        Ok(())
    }

    pub fn delete_model(&self, model_id: &str) -> Result<()> {
        println!("ModelManager: delete_model called for: {}", model_id);

        let model_info = {
            let models = self.available_models.lock().unwrap();
            models.get(model_id).cloned()
        };

        let model_info =
            model_info.ok_or_else(|| anyhow::anyhow!("Model not found: {}", model_id))?;

        println!("ModelManager: Found model info: {:?}", model_info);

        let model_path = self.models_dir.join(&model_info.filename);
        println!("ModelManager: Model path: {:?}", model_path);

        if model_path.exists() {
            println!("ModelManager: Deleting model file at: {:?}", model_path);
            fs::remove_file(&model_path)?;
            println!("ModelManager: Model file deleted successfully");
        } else {
            return Err(anyhow::anyhow!("Model file not found"));
        }

        // Update download status
        self.update_download_status()?;
        println!("ModelManager: Download status updated");

        Ok(())
    }

    pub fn get_model_path(&self, model_id: &str) -> Result<PathBuf> {
        let model_info = self
            .get_model_info(model_id)
            .ok_or_else(|| anyhow::anyhow!("Model not found: {}", model_id))?;

        if !model_info.is_downloaded {
            return Err(anyhow::anyhow!("Model not available: {}", model_id));
        }

        let model_path = self.models_dir.join(&model_info.filename);
        if model_path.exists() {
            Ok(model_path)
        } else {
            Err(anyhow::anyhow!("Model file not found: {}", model_id))
        }
    }
}