//! LLM Client Module
//!
//! Provides LLM API integration for memory extraction.
//! Supports multiple providers with a unified interface.
//!
//! Note: Some fields are reserved for future streaming and provider selection features

#![allow(dead_code)]

use serde::{Deserialize, Serialize};
use std::collections::HashMap;

// === Types ===

#[derive(Debug, Clone)]
pub struct LlmConfig {
    pub provider: String,
    pub api_key: String,
    pub endpoint: Option<String>,
    pub model: Option<String>,
}

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

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct LlmRequest {
    pub messages: Vec<LlmMessage>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub model: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub temperature: Option<f32>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub max_tokens: Option<u32>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct LlmResponse {
    pub content: String,
    pub model: Option<String>,
    pub usage: Option<LlmUsage>,
    pub finish_reason: Option<String>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct LlmUsage {
    pub prompt_tokens: u32,
    pub completion_tokens: u32,
    pub total_tokens: u32,
}

// === Provider Configuration ===

#[derive(Debug, Clone)]
pub struct ProviderConfig {
    pub name: String,
    pub endpoint: String,
    pub default_model: String,
    pub supports_streaming: bool,
}

pub fn get_provider_configs() -> HashMap<String, ProviderConfig> {
    let mut configs = HashMap::new();

    configs.insert(
        "doubao".to_string(),
        ProviderConfig {
            name: "Doubao (火山引擎)".to_string(),
            endpoint: "https://ark.cn-beijing.volces.com/api/v3".to_string(),
            default_model: "doubao-pro-32k".to_string(),
            supports_streaming: true,
        },
    );

    configs.insert(
        "openai".to_string(),
        ProviderConfig {
            name: "OpenAI".to_string(),
            endpoint: "https://api.openai.com/v1".to_string(),
            default_model: "gpt-4o".to_string(),
            supports_streaming: true,
        },
    );

    configs.insert(
        "anthropic".to_string(),
        ProviderConfig {
            name: "Anthropic".to_string(),
            endpoint: "https://api.anthropic.com/v1".to_string(),
            default_model: "claude-sonnet-4-20250514".to_string(),
            supports_streaming: false,
        },
    );

    configs
}

// === LLM Client ===

pub struct LlmClient {
    config: LlmConfig,
    provider_config: Option<ProviderConfig>,
}

impl LlmClient {
    pub fn new(config: LlmConfig) -> Self {
        let provider_config = get_provider_configs()
            .get(&config.provider)
            .cloned();

        Self {
            config,
            provider_config,
        }
    }

    /// Complete a chat completion request
    pub async fn complete(&self, messages: Vec<LlmMessage>) -> Result<LlmResponse, String> {
        let endpoint = self.config.endpoint.clone()
            .or_else(|| {
                self.provider_config
                    .as_ref()
                    .map(|c| c.endpoint.clone())
            })
            .unwrap_or_else(|| "https://ark.cn-beijing.volces.com/api/v3".to_string());

        let model = self.config.model.clone()
            .or_else(|| {
                self.provider_config
                    .as_ref()
                    .map(|c| c.default_model.clone())
            })
            .unwrap_or_else(|| "doubao-pro-32k".to_string());

        let request = LlmRequest {
            messages,
            model: Some(model),
            temperature: Some(0.3),
            max_tokens: Some(2000),
        };

        self.call_api(&endpoint, &request).await
    }

    /// Call LLM API
    async fn call_api(&self, endpoint: &str, request: &LlmRequest) -> Result<LlmResponse, String> {
        let client = reqwest::Client::new();

        let response = client
            .post(format!("{}/chat/completions", endpoint))
            .header("Authorization", format!("Bearer {}", self.config.api_key))
            .header("Content-Type", "application/json")
            .json(&request)
            .send()
            .await
            .map_err(|e| format!("LLM API request failed: {}", e))?;

        if !response.status().is_success() {
            let status = response.status();
            let body = response.text().await.unwrap_or_default();
            return Err(format!("LLM API error {}: {}", status, body));
        }

        let json: serde_json::Value = response
            .json()
            .await
            .map_err(|e| format!("Failed to parse LLM response: {}", e))?;

        // Parse response (OpenAI-compatible format)
        let content = json
            .get("choices")
            .and_then(|c| c.get(0))
            .and_then(|c| c.get("message"))
            .and_then(|m| m.get("content"))
            .and_then(|c| c.as_str())
            .ok_or("Invalid LLM response format")?
            .to_string();

        let usage = json
            .get("usage")
            .map(|u| LlmUsage {
                prompt_tokens: u.get("prompt_tokens").and_then(|v| v.as_u64()).unwrap_or(0) as u32,
                completion_tokens: u.get("completion_tokens").and_then(|v| v.as_u64()).unwrap_or(0) as u32,
                total_tokens: u.get("total_tokens").and_then(|v| v.as_u64()).unwrap_or(0) as u32,
            });

        Ok(LlmResponse {
            content,
            model: self.config.model.clone(),
            usage,
            finish_reason: json
                .get("choices")
                .and_then(|c| c.get(0))
                .and_then(|c| c.get("finish_reason"))
                .and_then(|v| v.as_str())
                .map(String::from),
        })
    }
}

// === Tauri Commands ===

#[tauri::command]
pub async fn llm_complete(
    provider: String,
    api_key: String,
    messages: Vec<LlmMessage>,
    model: Option<String>,
) -> Result<LlmResponse, String> {
    let config = LlmConfig {
        provider,
        api_key,
        endpoint: None,
        model,
    };

    let client = LlmClient::new(config);
    client.complete(messages).await
}

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

    #[test]
    fn test_provider_configs() {
        let configs = get_provider_configs();
        assert!(configs.contains_key("doubao"));
        assert!(configs.contains_key("openai"));
        assert!(configs.contains_key("anthropic"));
    }

    #[test]
    fn test_llm_client_creation() {
        let config = LlmConfig {
            provider: "doubao".to_string(),
            api_key: "test_key".to_string(),
            endpoint: None,
            model: None,
        };
        let client = LlmClient::new(config);
        assert!(client.provider_config.is_some());
    }
}