// Azure OpenAI client configuration.
//
// Provides `AzureConfig` builder for constructing an `OpenAI` client that
// targets Azure OpenAI deployments. Matches the Python SDK's `AzureOpenAI`
// constructor pattern.

use std::env;

use crate::client::OpenAI;
use crate::config::ClientConfig;
use crate::error::OpenAIError;

/// Default Azure API version.
const DEFAULT_API_VERSION: &str = "2024-10-21";

/// Configuration builder for Azure OpenAI deployments.
///
/// Azure OpenAI uses different URL construction and authentication compared
/// to the standard OpenAI API:
/// - URL: `{endpoint}/openai/deployments/{deployment}` or `{endpoint}/openai`
/// - Auth: `api-key` header (not `Authorization: Bearer`)
/// - Query: `api-version` parameter on every request
///
/// # Examples
///
/// ```ignore
/// use openai_oxide::{OpenAI, AzureConfig};
///
/// let client = OpenAI::azure(
///     AzureConfig::new()
///         .azure_endpoint("https://my-resource.openai.azure.com")
///         .azure_deployment("gpt-4")
///         .api_version("2024-10-21")
///         .api_key("my-azure-api-key")
/// )?;
///
/// // All resources work the same as with the standard client
/// let response = client.chat().completions().create(request).await?;
/// ```
#[derive(Debug, Clone, Default)]
pub struct AzureConfig {
    /// Azure endpoint URL, e.g. `https://my-resource.openai.azure.com`.
    pub azure_endpoint: Option<String>,

    /// Azure deployment name, e.g. `gpt-4`.
    pub azure_deployment: Option<String>,

    /// Azure API version, e.g. `2024-10-21`.
    pub api_version: Option<String>,

    /// Azure API key (mutually exclusive with `azure_ad_token`).
    pub api_key: Option<String>,

    /// Azure AD token for authentication (mutually exclusive with `api_key`).
    pub azure_ad_token: Option<String>,
}

impl AzureConfig {
    /// Create a new empty Azure configuration.
    #[must_use]
    pub fn new() -> Self {
        Self::default()
    }

    /// Set the Azure endpoint URL.
    ///
    /// Example: `https://my-resource.openai.azure.com`
    #[must_use]
    pub fn azure_endpoint(mut self, endpoint: impl Into<String>) -> Self {
        self.azure_endpoint = Some(endpoint.into());
        self
    }

    /// Set the Azure deployment name.
    ///
    /// When set, the base URL becomes `{endpoint}/openai/deployments/{deployment}`.
    /// When not set, the base URL is `{endpoint}/openai`.
    #[must_use]
    pub fn azure_deployment(mut self, deployment: impl Into<String>) -> Self {
        self.azure_deployment = Some(deployment.into());
        self
    }

    /// Set the Azure API version.
    ///
    /// Defaults to `2024-10-21` if not set and not in environment.
    #[must_use]
    pub fn api_version(mut self, version: impl Into<String>) -> Self {
        self.api_version = Some(version.into());
        self
    }

    /// Set the Azure API key.
    ///
    /// Mutually exclusive with `azure_ad_token`.
    #[must_use]
    pub fn api_key(mut self, key: impl Into<String>) -> Self {
        self.api_key = Some(key.into());
        self
    }

    /// Set the Azure AD token for authentication.
    ///
    /// Mutually exclusive with `api_key`. When using AD token auth,
    /// requests use `Authorization: Bearer {token}` instead of `api-key` header.
    #[must_use]
    pub fn azure_ad_token(mut self, token: impl Into<String>) -> Self {
        self.azure_ad_token = Some(token.into());
        self
    }

    /// Build an `OpenAI` client from this Azure configuration.
    ///
    /// # Errors
    ///
    /// Returns `OpenAIError::InvalidArgument` if:
    /// - No endpoint is provided (and `AZURE_OPENAI_ENDPOINT` is not set)
    /// - No credentials are provided (neither API key nor AD token)
    /// - Both `api_key` and `azure_ad_token` are set (mutually exclusive)
    pub fn build(self) -> Result<OpenAI, OpenAIError> {
        let endpoint = self.azure_endpoint.ok_or_else(|| {
            OpenAIError::InvalidArgument(
                "Azure endpoint is required. Set azure_endpoint() or AZURE_OPENAI_ENDPOINT env var"
                    .to_string(),
            )
        })?;

        let api_version = self
            .api_version
            .unwrap_or_else(|| DEFAULT_API_VERSION.to_string());

        // Validate mutual exclusivity
        if self.api_key.is_some() && self.azure_ad_token.is_some() {
            return Err(OpenAIError::InvalidArgument(
                "api_key and azure_ad_token are mutually exclusive; only one can be set"
                    .to_string(),
            ));
        }

        // Determine auth mode
        let (auth_key, use_azure_api_key_header) = match (&self.api_key, &self.azure_ad_token) {
            (Some(key), None) => (key.clone(), true),
            (None, Some(token)) => (token.clone(), false),
            (None, None) => {
                return Err(OpenAIError::InvalidArgument(
                    "Azure credentials required. Set api_key() or azure_ad_token()".to_string(),
                ));
            }
            _ => unreachable!(), // already checked above
        };

        // Build base URL
        let base_url = {
            let trimmed = endpoint.trim_end_matches('/');
            match &self.azure_deployment {
                Some(deployment) => format!("{trimmed}/openai/deployments/{deployment}"),
                None => format!("{trimmed}/openai"),
            }
        };

        // Build config with api-version as default query
        let config = ClientConfig::new(auth_key)
            .base_url(base_url)
            .default_query(vec![("api-version".to_string(), api_version)])
            .use_azure_api_key_header(use_azure_api_key_header);

        Ok(OpenAI::with_config(config))
    }

    /// Build an `OpenAI` client from environment variables.
    ///
    /// Reads:
    /// - `AZURE_OPENAI_API_KEY` — API key
    /// - `AZURE_OPENAI_ENDPOINT` — Azure endpoint URL
    /// - `OPENAI_API_VERSION` — API version (defaults to `2024-10-21`)
    /// - `AZURE_OPENAI_AD_TOKEN` — Azure AD token (alternative to API key)
    pub fn from_env() -> Result<OpenAI, OpenAIError> {
        let mut config = Self::new();

        if let Ok(endpoint) = env::var("AZURE_OPENAI_ENDPOINT") {
            config = config.azure_endpoint(endpoint);
        }

        if let Ok(key) = env::var("AZURE_OPENAI_API_KEY") {
            config = config.api_key(key);
        }

        if let Ok(token) = env::var("AZURE_OPENAI_AD_TOKEN") {
            config = config.azure_ad_token(token);
        }

        if let Ok(version) = env::var("OPENAI_API_VERSION") {
            config = config.api_version(version);
        }

        config.build()
    }
}

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

    // --- Task 2.1: AzureConfig builder URL construction ---

    #[test]
    fn test_azure_url_with_deployment() {
        let client = AzureConfig::new()
            .azure_endpoint("https://my-resource.openai.azure.com")
            .azure_deployment("gpt-4")
            .api_key("test-key")
            .build()
            .unwrap();

        assert_eq!(
            client.config.base_url,
            "https://my-resource.openai.azure.com/openai/deployments/gpt-4"
        );
    }

    #[test]
    fn test_azure_url_without_deployment() {
        let client = AzureConfig::new()
            .azure_endpoint("https://my-resource.openai.azure.com")
            .api_key("test-key")
            .build()
            .unwrap();

        assert_eq!(
            client.config.base_url,
            "https://my-resource.openai.azure.com/openai"
        );
    }

    #[test]
    fn test_azure_url_trailing_slash_stripped() {
        let client = AzureConfig::new()
            .azure_endpoint("https://my-resource.openai.azure.com/")
            .azure_deployment("gpt-4")
            .api_key("test-key")
            .build()
            .unwrap();

        assert_eq!(
            client.config.base_url,
            "https://my-resource.openai.azure.com/openai/deployments/gpt-4"
        );
    }

    #[test]
    fn test_azure_default_api_version() {
        let client = AzureConfig::new()
            .azure_endpoint("https://example.openai.azure.com")
            .api_key("test-key")
            .build()
            .unwrap();

        let query = client.options.query.as_ref().unwrap();
        assert!(
            query
                .iter()
                .any(|(k, v)| k == "api-version" && v == "2024-10-21")
        );
    }

    #[test]
    fn test_azure_custom_api_version() {
        let client = AzureConfig::new()
            .azure_endpoint("https://example.openai.azure.com")
            .api_key("test-key")
            .api_version("2024-06-01")
            .build()
            .unwrap();

        let query = client.options.query.as_ref().unwrap();
        assert!(
            query
                .iter()
                .any(|(k, v)| k == "api-version" && v == "2024-06-01")
        );
    }

    // --- Task 2.2: api-version query param on requests ---

    #[tokio::test]
    async fn test_azure_sends_api_version_query_param() {
        let mut server = mockito::Server::new_async().await;
        let mock = server
            .mock("GET", "/openai/models")
            .match_query(mockito::Matcher::AllOf(vec![mockito::Matcher::UrlEncoded(
                "api-version".into(),
                "2024-10-21".into(),
            )]))
            .with_status(200)
            .with_body(r#"{"data":[],"object":"list"}"#)
            .create_async()
            .await;

        let client = AzureConfig::new()
            .azure_endpoint(&server.url())
            .api_key("test-key")
            .build()
            .unwrap();

        #[derive(serde::Deserialize)]
        struct ListResp {
            object: String,
        }

        let resp: ListResp = client.get("/models").await.unwrap();
        assert_eq!(resp.object, "list");
        mock.assert_async().await;
    }

    // --- Task 2.3: Azure api-key header ---

    #[tokio::test]
    async fn test_azure_sends_api_key_header() {
        let mut server = mockito::Server::new_async().await;
        let mock = server
            .mock("GET", "/openai/test")
            .match_header("api-key", "my-azure-key")
            .match_query(mockito::Matcher::AllOf(vec![mockito::Matcher::UrlEncoded(
                "api-version".into(),
                "2024-10-21".into(),
            )]))
            .with_status(200)
            .with_body(r#"{"ok":true}"#)
            .create_async()
            .await;

        let client = AzureConfig::new()
            .azure_endpoint(&server.url())
            .api_key("my-azure-key")
            .build()
            .unwrap();

        #[derive(serde::Deserialize)]
        struct Resp {
            ok: bool,
        }

        let resp: Resp = client.get("/test").await.unwrap();
        assert!(resp.ok);
        mock.assert_async().await;
    }

    #[tokio::test]
    async fn test_azure_does_not_send_bearer_auth() {
        let mut server = mockito::Server::new_async().await;
        // Ensure no Authorization header is sent for api-key mode
        let mock = server
            .mock("GET", "/openai/test")
            .match_header("api-key", "my-azure-key")
            .match_header("authorization", mockito::Matcher::Missing)
            .match_query(mockito::Matcher::Any)
            .with_status(200)
            .with_body(r#"{"ok":true}"#)
            .create_async()
            .await;

        let client = AzureConfig::new()
            .azure_endpoint(&server.url())
            .api_key("my-azure-key")
            .build()
            .unwrap();

        #[derive(serde::Deserialize)]
        struct Resp {
            ok: bool,
        }

        let resp: Resp = client.get("/test").await.unwrap();
        assert!(resp.ok);
        mock.assert_async().await;
    }

    // --- Task 2.4: Azure AD token auth ---

    #[tokio::test]
    async fn test_azure_ad_token_sends_bearer() {
        let mut server = mockito::Server::new_async().await;
        let mock = server
            .mock("GET", "/openai/test")
            .match_header("authorization", "Bearer my-ad-token")
            .match_query(mockito::Matcher::Any)
            .with_status(200)
            .with_body(r#"{"ok":true}"#)
            .create_async()
            .await;

        let client = AzureConfig::new()
            .azure_endpoint(&server.url())
            .azure_ad_token("my-ad-token")
            .build()
            .unwrap();

        #[derive(serde::Deserialize)]
        struct Resp {
            ok: bool,
        }

        let resp: Resp = client.get("/test").await.unwrap();
        assert!(resp.ok);
        mock.assert_async().await;
    }

    // --- Task 2.5: Mutual exclusivity validation ---

    #[test]
    fn test_mutual_exclusivity_error() {
        let result = AzureConfig::new()
            .azure_endpoint("https://example.openai.azure.com")
            .api_key("key")
            .azure_ad_token("token")
            .build();

        assert!(result.is_err());
        let err = result.unwrap_err();
        assert!(
            err.to_string().contains("mutually exclusive"),
            "unexpected error: {err}"
        );
    }

    #[test]
    fn test_no_credentials_error() {
        let result = AzureConfig::new()
            .azure_endpoint("https://example.openai.azure.com")
            .build();

        assert!(result.is_err());
        let err = result.unwrap_err();
        assert!(
            err.to_string().contains("credentials required"),
            "unexpected error: {err}"
        );
    }

    #[test]
    fn test_no_endpoint_error() {
        let result = AzureConfig::new().api_key("key").build();

        assert!(result.is_err());
        let err = result.unwrap_err();
        assert!(
            err.to_string().contains("endpoint is required"),
            "unexpected error: {err}"
        );
    }

    // --- Task 2.6: from_env() ---

    #[test]
    fn test_from_env_reads_variables() {
        // SAFETY: test runs in a single thread context; no concurrent env access.
        unsafe {
            env::set_var("AZURE_OPENAI_ENDPOINT", "https://test.openai.azure.com");
            env::set_var("AZURE_OPENAI_API_KEY", "env-key");
            env::set_var("OPENAI_API_VERSION", "2024-06-01");
            env::remove_var("AZURE_OPENAI_AD_TOKEN");
        }

        let client = AzureConfig::from_env().unwrap();

        assert_eq!(
            client.config.base_url,
            "https://test.openai.azure.com/openai"
        );
        assert_eq!(client.config.api_key, "env-key");
        assert!(client.config.use_azure_api_key_header);

        let query = client.options.query.as_ref().unwrap();
        assert!(
            query
                .iter()
                .any(|(k, v)| k == "api-version" && v == "2024-06-01")
        );

        // Clean up
        unsafe {
            env::remove_var("AZURE_OPENAI_ENDPOINT");
            env::remove_var("AZURE_OPENAI_API_KEY");
            env::remove_var("OPENAI_API_VERSION");
        }
    }

    // --- Task 2.7: End-to-end chat completion through Azure client ---

    #[tokio::test]
    async fn test_azure_chat_completion_e2e() {
        let mut server = mockito::Server::new_async().await;
        let mock = server
            .mock("POST", "/openai/deployments/gpt-4/chat/completions")
            .match_header("api-key", "azure-key")
            .match_query(mockito::Matcher::AllOf(vec![mockito::Matcher::UrlEncoded(
                "api-version".into(),
                "2024-10-21".into(),
            )]))
            .with_status(200)
            .with_header("content-type", "application/json")
            .with_body(
                r#"{
                    "id": "chatcmpl-azure-123",
                    "object": "chat.completion",
                    "created": 1700000000,
                    "model": "gpt-4",
                    "choices": [{
                        "index": 0,
                        "message": {
                            "role": "assistant",
                            "content": "Hello from Azure!"
                        },
                        "finish_reason": "stop"
                    }],
                    "usage": {
                        "prompt_tokens": 10,
                        "completion_tokens": 5,
                        "total_tokens": 15
                    }
                }"#,
            )
            .create_async()
            .await;

        let client = AzureConfig::new()
            .azure_endpoint(&server.url())
            .azure_deployment("gpt-4")
            .api_key("azure-key")
            .build()
            .unwrap();

        use crate::types::chat::{ChatCompletionMessageParam, ChatCompletionRequest, UserContent};

        let request = ChatCompletionRequest::new(
            "gpt-4",
            vec![ChatCompletionMessageParam::User {
                content: UserContent::Text("Hello!".into()),
                name: None,
            }],
        );

        let response = client.chat().completions().create(request).await.unwrap();
        assert_eq!(response.id, "chatcmpl-azure-123");
        assert_eq!(
            response.choices[0].message.content.as_deref().unwrap_or(""),
            "Hello from Azure!"
        );
        mock.assert_async().await;
    }
}
