// This provider connects to a local Ollama instance for LLM inference.
// It will be actively used once providers are fully integrated with BridgeManager.
#![allow(dead_code)]

use async_trait::async_trait;
use serde::{Deserialize, Serialize};
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;
use tokio::sync::mpsc;

use crate::providers::traits::{
    LlmProvider, ModelInfo, ProviderCapabilities, ProviderConfig, ProviderMessage,
    ProviderStreamEvent, ProviderUsage, StreamCallback,
};

const DEFAULT_OLLAMA_URL: &str = "http://localhost:11434";

#[derive(Debug, Serialize)]
struct OllamaChatRequest {
    model: String,
    messages: Vec<OllamaMessage>,
    stream: bool,
    #[serde(skip_serializing_if = "Option::is_none")]
    system: Option<String>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
struct OllamaMessage {
    role: String,
    content: String,
}

#[derive(Debug, Deserialize)]
struct OllamaChatResponse {
    #[serde(default)]
    message: Option<OllamaResponseMessage>,
    #[serde(default)]
    done: bool,
    #[serde(default)]
    eval_count: Option<u64>,
    #[serde(default)]
    prompt_eval_count: Option<u64>,
}

#[derive(Debug, Deserialize)]
struct OllamaResponseMessage {
    #[serde(default)]
    content: String,
}

#[derive(Debug, Deserialize)]
struct OllamaTagsResponse {
    models: Vec<OllamaModelInfo>,
}

#[derive(Debug, Deserialize)]
struct OllamaModelInfo {
    name: String,
    #[serde(default)]
    details: Option<OllamaModelDetails>,
}

#[derive(Debug, Deserialize)]
struct OllamaModelDetails {
    #[serde(default)]
    parameter_size: Option<String>,
    #[serde(default)]
    family: Option<String>,
}

pub struct OllamaProvider {
    config: ProviderConfig,
    client: reqwest::Client,
    base_url: String,
    is_running: Arc<AtomicBool>,
    conversation_history: Vec<OllamaMessage>,
    cancel_tx: Option<mpsc::Sender<()>>,
}

impl OllamaProvider {
    pub fn new(config: ProviderConfig) -> Self {
        let base_url = config
            .api_base_url
            .clone()
            .unwrap_or_else(|| DEFAULT_OLLAMA_URL.to_string());

        Self {
            config,
            client: reqwest::Client::new(),
            base_url,
            is_running: Arc::new(AtomicBool::new(false)),
            conversation_history: Vec::new(),
            cancel_tx: None,
        }
    }

    async fn fetch_available_models(&self) -> Vec<ModelInfo> {
        let url = format!("{}/api/tags", self.base_url);

        match self.client.get(&url).send().await {
            Ok(response) => {
                if let Ok(tags) = response.json::<OllamaTagsResponse>().await {
                    tags.models
                        .into_iter()
                        .map(|m| {
                            let description = m.details.as_ref().map(|d| {
                                let mut desc_parts = Vec::new();
                                if let Some(ref family) = d.family {
                                    desc_parts.push(family.clone());
                                }
                                if let Some(ref size) = d.parameter_size {
                                    desc_parts.push(format!("{} parameters", size));
                                }
                                if desc_parts.is_empty() {
                                    "Local model".to_string()
                                } else {
                                    desc_parts.join(" - ")
                                }
                            });

                            ModelInfo {
                                id: m.name.clone(),
                                name: m.name,
                                description,
                                context_window: None,
                                input_cost_per_mtok: Some(0.0), // Local = free!
                                output_cost_per_mtok: Some(0.0),
                            }
                        })
                        .collect()
                } else {
                    default_ollama_models()
                }
            }
            Err(_) => default_ollama_models(),
        }
    }

    async fn stream_chat(
        &mut self,
        callback: Arc<StreamCallback>,
        cancel_rx: mpsc::Receiver<()>,
    ) -> Result<(), String> {
        let model = self
            .config
            .model
            .clone()
            .unwrap_or_else(|| "llama3.2".to_string());

        let request = OllamaChatRequest {
            model: model.clone(),
            messages: self.conversation_history.clone(),
            stream: true,
            system: self.config.custom_instructions.clone(),
        };

        let url = format!("{}/api/chat", self.base_url);

        let response = self
            .client
            .post(&url)
            .json(&request)
            .send()
            .await
            .map_err(|e| format!("Failed to connect to Ollama: {}", e))?;

        if !response.status().is_success() {
            let status = response.status();
            let error_text = response
                .text()
                .await
                .unwrap_or_else(|_| "Unknown error".to_string());
            return Err(format!("Ollama error ({}): {}", status, error_text));
        }

        let mut full_response = String::new();
        let mut total_input_tokens: u64 = 0;
        let mut total_output_tokens: u64 = 0;

        let mut stream = response.bytes_stream();
        let mut cancel_rx = cancel_rx;

        use futures_util::StreamExt;

        loop {
            tokio::select! {
                _ = cancel_rx.recv() => {
                    callback(ProviderStreamEvent::Disconnected);
                    return Ok(());
                }
                chunk = stream.next() => {
                    match chunk {
                        Some(Ok(bytes)) => {
                            let text = String::from_utf8_lossy(&bytes);

                            for line in text.lines() {
                                if line.trim().is_empty() {
                                    continue;
                                }

                                if let Ok(response) = serde_json::from_str::<OllamaChatResponse>(line) {
                                    if let Some(msg) = &response.message {
                                        if !msg.content.is_empty() {
                                            full_response.push_str(&msg.content);
                                            callback(ProviderStreamEvent::TextDelta {
                                                text: msg.content.clone(),
                                            });
                                        }
                                    }

                                    if let Some(tokens) = response.prompt_eval_count {
                                        total_input_tokens = tokens;
                                    }
                                    if let Some(tokens) = response.eval_count {
                                        total_output_tokens = tokens;
                                    }

                                    if response.done {
                                        self.conversation_history.push(OllamaMessage {
                                            role: "assistant".to_string(),
                                            content: full_response.clone(),
                                        });

                                        callback(ProviderStreamEvent::MessageComplete {
                                            content: vec![ProviderMessage::Text {
                                                content: full_response,
                                            }],
                                            usage: Some(ProviderUsage {
                                                input_tokens: total_input_tokens,
                                                output_tokens: total_output_tokens,
                                                model,
                                            }),
                                            stop_reason: Some("end_turn".to_string()),
                                        });

                                        return Ok(());
                                    }
                                }
                            }
                        }
                        Some(Err(e)) => {
                            return Err(format!("Stream error: {}", e));
                        }
                        None => {
                            break;
                        }
                    }
                }
            }
        }

        Ok(())
    }
}

#[async_trait]
impl LlmProvider for OllamaProvider {
    fn name(&self) -> &'static str {
        "Ollama"
    }

    fn capabilities(&self) -> ProviderCapabilities {
        ProviderCapabilities {
            supports_streaming: true,
            supports_tools: false, // Ollama doesn't support tools natively yet
            supports_vision: true, // Some models support vision
            supports_thinking: false,
            supports_mcp: false,
            supports_resume_session: false,
            max_context_tokens: None, // Varies by model
            available_models: default_ollama_models(),
        }
    }

    async fn start(&mut self, callback: StreamCallback) -> Result<(), String> {
        if self.is_running.load(Ordering::SeqCst) {
            return Err("Provider already running".to_string());
        }

        // Check if Ollama is reachable
        let url = format!("{}/api/tags", self.base_url);
        self.client.get(&url).send().await.map_err(|e| {
            format!(
                "Cannot connect to Ollama at {}. Is it running? Error: {}",
                self.base_url, e
            )
        })?;

        self.is_running.store(true, Ordering::SeqCst);
        self.conversation_history.clear();

        // Create cancellation channel
        let (tx, _rx) = mpsc::channel(1);
        self.cancel_tx = Some(tx);

        callback(ProviderStreamEvent::Connected { session_id: None });

        // Fetch and report available models
        let models = self.fetch_available_models().await;
        if !models.is_empty() {
            eprintln!(
                "[Ollama] Available models: {:?}",
                models.iter().map(|m| &m.id).collect::<Vec<_>>()
            );
        }

        Ok(())
    }

    async fn stop(&mut self) -> Result<(), String> {
        self.is_running.store(false, Ordering::SeqCst);
        self.conversation_history.clear();

        if let Some(tx) = self.cancel_tx.take() {
            let _ = tx.send(()).await;
        }

        Ok(())
    }

    fn is_running(&self) -> bool {
        self.is_running.load(Ordering::SeqCst)
    }

    async fn send_message(&mut self, message: &str) -> Result<(), String> {
        if !self.is_running.load(Ordering::SeqCst) {
            return Err("Provider not running".to_string());
        }

        // Add user message to history
        self.conversation_history.push(OllamaMessage {
            role: "user".to_string(),
            content: message.to_string(),
        });

        // Create a new cancel channel for this request
        let (tx, _rx) = mpsc::channel(1);
        self.cancel_tx = Some(tx);

        // We need a callback here, but we don't have access to it in send_message
        // This is a limitation of the current trait design
        // For now, we'll need to refactor to handle streaming properly
        // The callback should be stored from the start() call

        // For the MVP, we'll emit events directly
        // In a real implementation, we'd need to restructure this

        Err("send_message needs refactoring to work with stored callback".to_string())
    }

    async fn send_tool_result(
        &mut self,
        _tool_use_id: &str,
        _result: serde_json::Value,
        _is_error: bool,
    ) -> Result<(), String> {
        // Ollama doesn't support tool use natively
        Err("Ollama does not support tool use".to_string())
    }

    fn get_model(&self) -> Option<String> {
        self.config.model.clone()
    }

    fn get_working_directory(&self) -> &str {
        &self.config.working_directory
    }

    async fn interrupt(&mut self) -> Result<(), String> {
        if let Some(tx) = self.cancel_tx.take() {
            let _ = tx.send(()).await;
        }
        self.is_running.store(false, Ordering::SeqCst);
        Ok(())
    }
}

fn default_ollama_models() -> Vec<ModelInfo> {
    vec![
        ModelInfo {
            id: "llama3.2".to_string(),
            name: "Llama 3.2".to_string(),
            description: Some("Meta's latest compact model".to_string()),
            context_window: Some(128_000),
            input_cost_per_mtok: Some(0.0),
            output_cost_per_mtok: Some(0.0),
        },
        ModelInfo {
            id: "llama3.2:1b".to_string(),
            name: "Llama 3.2 1B".to_string(),
            description: Some("Smallest Llama 3.2 variant".to_string()),
            context_window: Some(128_000),
            input_cost_per_mtok: Some(0.0),
            output_cost_per_mtok: Some(0.0),
        },
        ModelInfo {
            id: "qwen2.5-coder".to_string(),
            name: "Qwen 2.5 Coder".to_string(),
            description: Some("Alibaba's coding-focused model".to_string()),
            context_window: Some(32_000),
            input_cost_per_mtok: Some(0.0),
            output_cost_per_mtok: Some(0.0),
        },
        ModelInfo {
            id: "deepseek-coder-v2".to_string(),
            name: "DeepSeek Coder V2".to_string(),
            description: Some("DeepSeek's coding model".to_string()),
            context_window: Some(128_000),
            input_cost_per_mtok: Some(0.0),
            output_cost_per_mtok: Some(0.0),
        },
        ModelInfo {
            id: "mistral".to_string(),
            name: "Mistral 7B".to_string(),
            description: Some("Fast and capable".to_string()),
            context_window: Some(32_000),
            input_cost_per_mtok: Some(0.0),
            output_cost_per_mtok: Some(0.0),
        },
        ModelInfo {
            id: "gemma2".to_string(),
            name: "Gemma 2".to_string(),
            description: Some("Google's open model".to_string()),
            context_window: Some(8_000),
            input_cost_per_mtok: Some(0.0),
            output_cost_per_mtok: Some(0.0),
        },
    ]
}

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

    #[test]
    fn test_provider_name() {
        let config = ProviderConfig::default();
        let provider = OllamaProvider::new(config);
        assert_eq!(provider.name(), "Ollama");
    }

    #[test]
    fn test_capabilities() {
        let config = ProviderConfig::default();
        let provider = OllamaProvider::new(config);
        let caps = provider.capabilities();

        assert!(caps.supports_streaming);
        assert!(!caps.supports_tools);
        assert!(!caps.supports_mcp);
        assert!(!caps.supports_resume_session);
        assert!(!caps.available_models.is_empty());
    }

    #[test]
    fn test_default_url() {
        let config = ProviderConfig::default();
        let provider = OllamaProvider::new(config);
        assert_eq!(provider.base_url, DEFAULT_OLLAMA_URL);
    }

    #[test]
    fn test_custom_url() {
        let config = ProviderConfig {
            api_base_url: Some("http://custom:8080".to_string()),
            ..Default::default()
        };
        let provider = OllamaProvider::new(config);
        assert_eq!(provider.base_url, "http://custom:8080");
    }

    #[test]
    fn test_is_running_initial() {
        let config = ProviderConfig::default();
        let provider = OllamaProvider::new(config);
        assert!(!provider.is_running());
    }

    #[test]
    fn test_default_ollama_models() {
        let models = default_ollama_models();
        assert!(!models.is_empty());

        // All models should be free (local)
        for model in &models {
            assert_eq!(model.input_cost_per_mtok, Some(0.0));
            assert_eq!(model.output_cost_per_mtok, Some(0.0));
        }

        // Should include llama
        assert!(models.iter().any(|m| m.id.contains("llama")));
    }

    #[test]
    fn test_ollama_message_serialization() {
        let msg = OllamaMessage {
            role: "user".to_string(),
            content: "Hello!".to_string(),
        };

        let json = serde_json::to_string(&msg).unwrap();
        assert!(json.contains("\"role\":\"user\""));
        assert!(json.contains("\"content\":\"Hello!\""));
    }

    #[test]
    fn test_chat_request_serialization() {
        let request = OllamaChatRequest {
            model: "llama3.2".to_string(),
            messages: vec![OllamaMessage {
                role: "user".to_string(),
                content: "Test".to_string(),
            }],
            stream: true,
            system: Some("You are helpful".to_string()),
        };

        let json = serde_json::to_string(&request).unwrap();
        assert!(json.contains("\"model\":\"llama3.2\""));
        assert!(json.contains("\"stream\":true"));
        assert!(json.contains("\"system\":\"You are helpful\""));
    }

    #[test]
    fn test_chat_request_without_system() {
        let request = OllamaChatRequest {
            model: "llama3.2".to_string(),
            messages: vec![],
            stream: true,
            system: None,
        };

        let json = serde_json::to_string(&request).unwrap();
        // system should be omitted when None
        assert!(!json.contains("\"system\""));
    }
}