//! GyanDoot Providers — LLM provider abstraction layer.
//!
//! Defines the [`Provider`] trait and implementations for OpenAI, Anthropic,
//! Ollama, and other providers. Each implementation handles authentication,
//! request formatting, response parsing, and streaming.
//!
//! The [`ProviderFactory`] creates provider instances from
//! [`gyandoot_core::ProviderConfig`].

use async_trait::async_trait;
use gyandoot_core::{ConversationContext, ProviderResult, ToolCall};

pub mod openai;
pub mod anthropic;
pub mod ollama;
pub mod streaming;
pub mod gemini;
pub mod deepseek;
pub mod openrouter;
pub mod groq;

// ─── Re-exports ───────────────────────────────────────────────────────────

pub use openai::OpenAIProvider;
pub use anthropic::AnthropicProvider;
pub use ollama::OllamaProvider;
pub use gemini::GeminiProvider;
pub use deepseek::DeepSeekProvider;
pub use openrouter::OpenRouterProvider;
pub use groq::GroqProvider;
pub use streaming::{SseParser, StreamEvent, TokenStream, collect_stream};

// ─── ProviderResponse ─────────────────────────────────────────────────────

/// A provider response containing the generated text and any tool calls.
#[derive(Debug, Clone)]
pub struct ProviderResponse {
    pub content: String,
    pub tool_calls: Option<Vec<ToolCall>>,
    pub finish_reason: String,
}

impl ProviderResponse {
    /// Create a new provider response with text content only.
    pub fn new(content: impl Into<String>) -> Self {
        Self {
            content: content.into(),
            tool_calls: None,
            finish_reason: "stop".to_string(),
        }
    }

    /// Create a provider response with tool calls.
    pub fn with_tool_calls(
        content: impl Into<String>,
        calls: Vec<ToolCall>,
        finish_reason: impl Into<String>,
    ) -> Self {
        Self {
            content: content.into(),
            tool_calls: Some(calls),
            finish_reason: finish_reason.into(),
        }
    }

    /// Return true if this response contains tool calls.
    pub fn has_tool_calls(&self) -> bool {
        self.tool_calls.as_ref().map_or(false, |c| !c.is_empty())
    }
}

// ─── Provider trait ───────────────────────────────────────────────────────

/// The trait that all LLM providers must implement.
#[async_trait]
pub trait Provider: Send + Sync {
    /// Send a chat completion request and return the full response.
    async fn chat(&self, context: ConversationContext) -> ProviderResult<ProviderResponse>;

    /// Send a chat completion request with streaming response.
    ///
    /// Each item in the stream represents a text delta. Use
    /// [`streaming::collect_stream`] to aggregate the full text.
    async fn chat_stream(
        &self,
        context: ConversationContext,
    ) -> ProviderResult<Box<dyn tokio_stream::Stream<Item = ProviderResult<String>> + Send + Unpin>>;

    /// Return the list of models available for this provider.
    async fn models(&self) -> ProviderResult<Vec<String>> {
        // Default: return an empty list; providers can override.
        let _ = self;
        Ok(Vec::new())
    }

    /// Return whether this provider supports tool/function calling.
    fn supports_tools(&self) -> bool {
        true
    }
}

// ─── ProviderKind (runtime enum) ──────────────────────────────────────────

/// Runtime provider kind for factory dispatch.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ProviderKind {
    OpenAI,
    Anthropic,
    Ollama,
    Gemini,
    DeepSeek,
    OpenRouter,
    Groq,
}

impl ProviderKind {
    /// Parse from a string, case-insensitive.
    pub fn from_str(s: &str) -> Option<Self> {
        match s.to_lowercase().as_str() {
            "openai" => Some(ProviderKind::OpenAI),
            "anthropic" => Some(ProviderKind::Anthropic),
            "ollama" => Some(ProviderKind::Ollama),
            "gemini" => Some(ProviderKind::Gemini),
            "deepseek" => Some(ProviderKind::DeepSeek),
            "openrouter" => Some(ProviderKind::OpenRouter),
            "groq" => Some(ProviderKind::Groq),
            _ => None,
        }
    }

    /// Return the canonical string name.
    pub fn as_str(&self) -> &'static str {
        match self {
            ProviderKind::OpenAI => "openai",
            ProviderKind::Anthropic => "anthropic",
            ProviderKind::Ollama => "ollama",
            ProviderKind::Gemini => "gemini",
            ProviderKind::DeepSeek => "deepseek",
            ProviderKind::OpenRouter => "openrouter",
            ProviderKind::Groq => "groq",
        }
    }
}

impl std::fmt::Display for ProviderKind {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.as_str())
    }
}

// ─── ProviderFactory ───────────────────────────────────────────────────────

/// Factory for creating provider instances from configuration.
pub struct ProviderFactory;

impl ProviderFactory {
    /// Create a provider from a [`gyandoot_core::ProviderRootConfig`].
    pub fn create(config: &gyandoot_core::ProviderRootConfig) -> ProviderResult<Box<dyn Provider>> {
        let kind = ProviderKind::from_str(&config.default)
            .ok_or_else(|| gyandoot_core::ProviderError::Api {
                status: 0,
                message: format!("Unknown provider name: {}", config.default),
            })?;

        Self::create_from_kind(kind, config)
    }

    /// Create a provider from a [`ProviderKind`] and config.
    pub fn create_from_kind(
        kind: ProviderKind,
        config: &gyandoot_core::ProviderRootConfig,
    ) -> ProviderResult<Box<dyn Provider>> {
        match kind {
            ProviderKind::OpenAI => {
                let cfg = config.openai.as_ref().ok_or_else(|| gyandoot_core::ProviderError::Api {
                    status: 0,
                    message: "OpenAI config not found".to_string(),
                })?;
                Ok(Box::new(openai::OpenAIProvider::new(
                    cfg.api_key.clone(),
                    cfg.model.clone(),
                    cfg.base_url.clone(),
                )))
            }
            ProviderKind::Anthropic => {
                let cfg = config.anthropic.as_ref().ok_or_else(|| gyandoot_core::ProviderError::Api {
                    status: 0,
                    message: "Anthropic config not found".to_string(),
                })?;
                Ok(Box::new(anthropic::AnthropicProvider::new(
                    cfg.api_key.clone(),
                    cfg.model.clone(),
                )))
            }
            ProviderKind::Ollama => {
                let cfg = config.ollama.as_ref().ok_or_else(|| gyandoot_core::ProviderError::Api {
                    status: 0,
                    message: "Ollama config not found".to_string(),
                })?;
                Ok(Box::new(ollama::OllamaProvider::new(
                    cfg.base_url.clone(),
                    cfg.model.clone(),
                    cfg.api_key.clone(),
                )))
            }
            ProviderKind::Gemini => {
                let cfg = config.openai.as_ref().ok_or_else(|| gyandoot_core::ProviderError::Api {
                    status: 0,
                    message: "Gemini config not found (use openai section)".to_string(),
                })?;
                Ok(Box::new(gemini::GeminiProvider::new(
                    cfg.api_key.clone(),
                    cfg.model.clone(),
                    cfg.base_url.clone(),
                )))
            }
            ProviderKind::DeepSeek => {
                let cfg = config.openai.as_ref().ok_or_else(|| gyandoot_core::ProviderError::Api {
                    status: 0,
                    message: "DeepSeek config not found (use openai section)".to_string(),
                })?;
                Ok(Box::new(deepseek::DeepSeekProvider::new(
                    cfg.api_key.clone(),
                    cfg.model.clone(),
                    cfg.base_url.clone(),
                )))
            }
            ProviderKind::OpenRouter => {
                let cfg = config.openai.as_ref().ok_or_else(|| gyandoot_core::ProviderError::Api {
                    status: 0,
                    message: "OpenRouter config not found (use openai section)".to_string(),
                })?;
                Ok(Box::new(openrouter::OpenRouterProvider::new(
                    cfg.api_key.clone(),
                    cfg.model.clone(),
                    cfg.base_url.clone(),
                )))
            }
            ProviderKind::Groq => {
                let cfg = config.openai.as_ref().ok_or_else(|| gyandoot_core::ProviderError::Api {
                    status: 0,
                    message: "Groq config not found (use openai section)".to_string(),
                })?;
                Ok(Box::new(groq::GroqProvider::new(
                    cfg.api_key.clone(),
                    cfg.model.clone(),
                    cfg.base_url.clone(),
                )))
            }
        }
    }

    /// Create a provider from just a kind name string and minimal config.
    pub fn from_name(
        name: &str,
        api_key: &str,
        model: &str,
    ) -> ProviderResult<Box<dyn Provider>> {
        let kind = ProviderKind::from_str(name)
            .ok_or_else(|| gyandoot_core::ProviderError::Api {
                status: 0,
                message: format!("Unknown provider name: {name}"),
            })?;

        let config = gyandoot_core::ProviderRootConfig {
            default: name.to_string(),
            openai: if matches!(kind, ProviderKind::OpenAI | ProviderKind::DeepSeek | ProviderKind::OpenRouter | ProviderKind::Gemini | ProviderKind::Groq) {
                Some(gyandoot_core::OpenAIConfig {
                    api_key: api_key.to_string(),
                    model: model.to_string(),
                    base_url: Some(default_base_url(&kind)),
                    max_retries: 3,
                })
            } else {
                None
            },
            anthropic: if matches!(kind, ProviderKind::Anthropic) {
                Some(gyandoot_core::AnthropicConfig {
                    api_key: api_key.to_string(),
                    model: model.to_string(),
                    max_retries: 3,
                })
            } else {
                None
            },
            ollama: if matches!(kind, ProviderKind::Ollama) {
                Some(gyandoot_core::OllamaConfig {
                    base_url: default_base_url(&kind),
                    model: model.to_string(),
                    api_key: None,
                    max_retries: 2,
                })
            } else {
                None
            },
        };

        Self::create_from_kind(kind, &config)
    }
}

/// Default base URL for each provider kind.
fn default_base_url(kind: &ProviderKind) -> String {
    match kind {
        ProviderKind::OpenAI => "https://api.openai.com/v1".to_string(),
        ProviderKind::Anthropic => "https://api.anthropic.com".to_string(),
        ProviderKind::Ollama => "http://localhost:11434".to_string(),
        ProviderKind::Gemini => "https://generativelanguage.googleapis.com/v1".to_string(),
        ProviderKind::DeepSeek => "https://api.deepseek.com/v1".to_string(),
        ProviderKind::OpenRouter => "https://openrouter.ai/api/v1".to_string(),
        ProviderKind::Groq => "https://api.groq.com/openai/v1".to_string(),
    }
}

// ─── Tests ────────────────────────────────────────────────────────────────

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

    #[test]
    fn test_provider_kind_roundtrip() {
        for kind in &[
            ProviderKind::OpenAI,
            ProviderKind::Anthropic,
            ProviderKind::Ollama,
            ProviderKind::Gemini,
            ProviderKind::DeepSeek,
            ProviderKind::OpenRouter,
            ProviderKind::Groq,
        ] {
            let s = kind.to_string();
            let parsed = ProviderKind::from_str(&s).unwrap();
            assert_eq!(*kind, parsed);
        }
    }

    #[test]
    fn test_provider_response_has_tool_calls() {
        let r = ProviderResponse::new("hello");
        assert!(!r.has_tool_calls());

        let r = ProviderResponse::with_tool_calls(
            "",
            vec![ToolCall::new("1", "test", serde_json::Value::Null)],
            "tool_calls",
        );
        assert!(r.has_tool_calls());
    }

    #[test]
    fn test_default_base_urls() {
        assert!(default_base_url(&ProviderKind::OpenAI).contains("openai.com"));
        assert!(default_base_url(&ProviderKind::Anthropic).contains("anthropic.com"));
        assert!(default_base_url(&ProviderKind::Ollama).contains("localhost"));
    }

    #[test]
    fn test_factory_from_name() {
        let provider = ProviderFactory::from_name("openai", "sk-test", "gpt-4o").unwrap();
        assert!(provider.supports_tools());
    }

    #[test]
    fn test_factory_invalid_name() {
        let result = ProviderFactory::from_name("nonexistent", "", "");
        assert!(result.is_err());
    }

    #[test]
    fn test_provider_kind_unknown_string() {
        assert_eq!(ProviderKind::from_str("unknown"), None);
    }
}