flyllm 0.4.1

use crate::load_balancer::tasks::TaskDefinition;
use crate::providers::instances::{LlmInstance, BaseInstance};
use crate::providers::types::{LlmRequest, LlmResponse, LlmStream, StreamChunk, TokenUsage, Message};
use crate::providers::streaming::OpenAIStreamChunk;
use crate::errors::{LlmError, LlmResult};
use crate::constants;

use std::collections::HashMap;
use async_trait::async_trait;
use reqwest::header;
use serde::{Serialize, Deserialize};
use futures::StreamExt;

/// Provider implementation for Mistral AI's API
pub struct MistralInstance {
    base: BaseInstance,
}

/// Request structure for Mistral AI's chat completion API
#[derive(Serialize)]
struct MistralRequest {
    model: String,
    messages: Vec<Message>,
    #[serde(skip_serializing_if = "Option::is_none")]
    temperature: Option<f32>,
    #[serde(skip_serializing_if = "Option::is_none")]
    max_tokens: Option<u32>,
    #[serde(skip_serializing_if = "Option::is_none")]
    stream: Option<bool>,
}

/// Response structure from Mistral AI's chat completion API
#[derive(Deserialize, Debug)]
struct MistralResponse {
    id: String,
    model: String,
    object: String,
    created: u64,
    choices: Vec<MistralChoice>,
    usage: Option<MistralUsage>, 
}

/// Individual choice from Mistral's response
#[derive(Deserialize, Debug)]
struct MistralChoice {
    index: u32,  // Removed underscore prefix
    message: Message,
    finish_reason: Option<String>,
}

/// Token usage information from Mistral
#[derive(Deserialize, Debug)]
struct MistralUsage {
    prompt_tokens: u32,
    completion_tokens: u32,
    total_tokens: u32,
}

impl MistralInstance {
    /// Creates a new Mistral provider instance
    ///
    /// # Parameters
    /// * `api_key` - Mistral API key
    /// * `model` - Default model to use (e.g. "mistral-large")
    /// * `supported_tasks` - Map of tasks this provider supports
    /// * `enabled` - Whether this provider is enabled
    pub fn new(api_key: String, model: String, supported_tasks: HashMap<String, TaskDefinition>, enabled: bool) -> Self {
        let base = BaseInstance::new("mistral".to_string(), api_key, model, supported_tasks, enabled);
        Self { base }
    }
}

#[async_trait]
impl LlmInstance for MistralInstance {
    /// Generates a completion using Mistral AI's API
    ///
    /// # Parameters
    /// * `request` - The LLM request containing messages and parameters
    ///
    /// # Returns
    /// * `LlmResult<LlmResponse>` - The response from the model or an error
    async fn generate(&self, request: &LlmRequest) -> LlmResult<LlmResponse> {
        if !self.base.is_enabled() {
            return Err(LlmError::ProviderDisabled("Mistral".to_string()));
        }

        let mut headers = header::HeaderMap::new();
        headers.insert(
            header::AUTHORIZATION,
            header::HeaderValue::from_str(&format!("Bearer {}", self.base.api_key()))
                .map_err(|e| LlmError::ConfigError(format!("Invalid API key format: {}", e)))?,
        );
        headers.insert(
            header::CONTENT_TYPE,
            header::HeaderValue::from_static("application/json"),
        );
        headers.insert(
            header::ACCEPT,
            header::HeaderValue::from_static("application/json"),
        );

        let model = request.model.clone().unwrap_or_else(|| self.base.model().to_string());

        if request.messages.is_empty() {
            return Err(LlmError::ApiError("Mistral requires at least one message".to_string()));
        }

        let mistral_request = MistralRequest {
            model,
            messages: request.messages.iter().map(|m| Message {
                 role: match m.role.as_str() {
                    "system" | "user" | "assistant" => m.role.clone(),
                    _ => "user".to_string(),
                 },
                 content: m.content.clone()
            }).collect(),
            temperature: request.temperature,
            max_tokens: request.max_tokens,
            stream: None,
        };

        let response = self.base.client()
            .post(constants::MISTRAL_API_ENDPOINT) 
            .headers(headers)
            .json(&mistral_request)
            .send()
            .await?;

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

        // Debug: Log raw response body for inspection if needed
        let response_body = response.text().await
            .map_err(|e| LlmError::ApiError(format!("Failed to read Mistral response body: {}", e)))?;
        
        // Try to parse the response as JSON
        let mistral_response: MistralResponse = serde_json::from_str(&response_body)
            .map_err(|e| {
                // Provide more context in the error message
                LlmError::ApiError(format!(
                    "Failed to parse Mistral JSON response: {}. Response body: {}",
                    e, 
                    if response_body.len() > 200 { 
                        format!("{}... (truncated)", &response_body[..200]) 
                    } else { 
                        response_body.clone() 
                    }
                ))
            })?;

        if mistral_response.choices.is_empty() {
            return Err(LlmError::ApiError("No choices returned from Mistral".to_string()));
        }

        let choice = &mistral_response.choices[0];

        let usage = mistral_response.usage.map(|u| TokenUsage {
            prompt_tokens: u.prompt_tokens,
            completion_tokens: u.completion_tokens,
            total_tokens: u.total_tokens,
        });

        Ok(LlmResponse {
            content: choice.message.content.clone(),
            model: mistral_response.model,
            usage,
        })
    }

    async fn generate_stream(&self, request: &LlmRequest) -> LlmResult<LlmStream> {
        if !self.base.is_enabled() {
            return Err(LlmError::ProviderDisabled("Mistral".to_string()));
        }

        let mut headers = header::HeaderMap::new();
        headers.insert(
            header::AUTHORIZATION,
            header::HeaderValue::from_str(&format!("Bearer {}", self.base.api_key()))
                .map_err(|e| LlmError::ConfigError(format!("Invalid API key format: {}", e)))?,
        );
        headers.insert(
            header::CONTENT_TYPE,
            header::HeaderValue::from_static("application/json"),
        );
        headers.insert(
            header::ACCEPT,
            header::HeaderValue::from_static("application/json"),
        );

        let model = request.model.clone().unwrap_or_else(|| self.base.model().to_string());

        if request.messages.is_empty() {
            return Err(LlmError::ApiError("Mistral requires at least one message".to_string()));
        }

        let mistral_request = MistralRequest {
            model,
            messages: request.messages.iter().map(|m| Message {
                role: match m.role.as_str() {
                    "system" | "user" | "assistant" => m.role.clone(),
                    _ => "user".to_string(),
                },
                content: m.content.clone()
            }).collect(),
            temperature: request.temperature,
            max_tokens: request.max_tokens,
            stream: Some(true),
        };

        let response = self.base.client()
            .post(constants::MISTRAL_API_ENDPOINT)
            .headers(headers)
            .json(&mistral_request)
            .send()
            .await?;

        let response_status = response.status();

        if response_status.as_u16() == 429 {
            let error_text = response.text().await
                .unwrap_or_else(|_| "Rate limit exceeded".to_string());
            return Err(LlmError::RateLimit(format!("Mistral rate limit: {}", error_text)));
        }

        if !response_status.is_success() {
            let error_text = response.text().await
                .unwrap_or_else(|_| format!("Unknown error. Status: {}", response_status));
            return Err(LlmError::ApiError(format!("Mistral API error: {}", error_text)));
        }

        let byte_stream = response.bytes_stream();

        let chunk_stream = byte_stream
            .map(|result| result.map_err(|e| LlmError::RequestError(e)))
            .flat_map(|result| {
                match result {
                    Ok(bytes) => {
                        let text = String::from_utf8_lossy(&bytes);
                        let chunks: Vec<Result<StreamChunk, LlmError>> = text
                            .lines()
                            .filter_map(|line| {
                                let line = line.trim();
                                if line.starts_with("data: ") {
                                    let data = &line[6..];
                                    if data == "[DONE]" {
                                        return None;
                                    }
                                    match serde_json::from_str::<OpenAIStreamChunk>(data) {
                                        Ok(chunk) => chunk.to_stream_chunk().map(Ok),
                                        Err(e) => Some(Err(LlmError::ParseError(
                                            format!("Failed to parse streaming chunk: {}", e)
                                        ))),
                                    }
                                } else {
                                    None
                                }
                            })
                            .collect();
                        futures::stream::iter(chunks)
                    }
                    Err(e) => futures::stream::iter(vec![Err(e)])
                }
            });

        Ok(Box::pin(chunk_stream))
    }

    fn supports_streaming(&self) -> bool {
        true
    }

    /// Returns provider name
    fn get_name(&self) -> &str {
        self.base.name()
    }

    /// Returns current model name
    fn get_model(&self) -> &str {
        self.base.model()
    }

    /// Returns supported tasks for this provider
    fn get_supported_tasks(&self) -> &HashMap<String, TaskDefinition> {
        &self.base.supported_tasks()
    }

    /// Returns whether this provider is enabled
    fn is_enabled(&self) -> bool {
        self.base.is_enabled()
    }
}