//! Compute integration for edge functions and SSR.
//!
//! Enables serverless compute capabilities for hosted websites:
//! - Edge functions (API routes, middleware)
//! - Server-side rendering (SSR)
//! - Image optimization
//! - AI/ML inference at the edge

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

/// Edge function configuration.
#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct EdgeFunctionConfig {
    /// Function name/path.
    pub name: String,
    /// Runtime (wasm, js).
    pub runtime: EdgeRuntime,
    /// Memory limit in MB.
    pub memory_mb: u32,
    /// Timeout in seconds.
    pub timeout_secs: u32,
    /// Environment variables.
    pub env: HashMap<String, String>,
    /// Region preferences.
    pub regions: Vec<String>,
}

impl Default for EdgeFunctionConfig {
    fn default() -> Self {
        Self {
            name: String::new(),
            runtime: EdgeRuntime::Wasm,
            memory_mb: 128,
            timeout_secs: 10,
            env: HashMap::new(),
            regions: vec!["global".to_string()],
        }
    }
}

/// Supported edge runtimes.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub enum EdgeRuntime {
    /// WebAssembly (via synor-compute WASM workers).
    Wasm,
    /// JavaScript (V8 isolates).
    JavaScript,
    /// Python (via WebAssembly).
    Python,
}

/// Edge function request.
#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct EdgeRequest {
    /// HTTP method.
    pub method: String,
    /// Request path.
    pub path: String,
    /// Query parameters.
    pub query: HashMap<String, String>,
    /// Headers.
    pub headers: HashMap<String, String>,
    /// Request body.
    pub body: Option<Vec<u8>>,
    /// Client IP.
    pub client_ip: Option<String>,
    /// Geolocation.
    pub geo: Option<GeoInfo>,
}

/// Geolocation information.
#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct GeoInfo {
    /// Country code.
    pub country: String,
    /// Region/state.
    pub region: Option<String>,
    /// City.
    pub city: Option<String>,
    /// Latitude.
    pub latitude: Option<f64>,
    /// Longitude.
    pub longitude: Option<f64>,
}

/// Edge function response.
#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct EdgeResponse {
    /// HTTP status code.
    pub status: u16,
    /// Response headers.
    pub headers: HashMap<String, String>,
    /// Response body.
    pub body: Vec<u8>,
}

impl EdgeResponse {
    /// Create a 200 OK response.
    pub fn ok(body: impl Into<Vec<u8>>) -> Self {
        Self {
            status: 200,
            headers: HashMap::new(),
            body: body.into(),
        }
    }

    /// Create a JSON response.
    pub fn json<T: Serialize>(data: &T) -> Result<Self, serde_json::Error> {
        let body = serde_json::to_vec(data)?;
        let mut headers = HashMap::new();
        headers.insert("Content-Type".to_string(), "application/json".to_string());
        Ok(Self {
            status: 200,
            headers,
            body,
        })
    }

    /// Create a redirect response.
    pub fn redirect(location: &str, permanent: bool) -> Self {
        let mut headers = HashMap::new();
        headers.insert("Location".to_string(), location.to_string());
        Self {
            status: if permanent { 301 } else { 302 },
            headers,
            body: Vec::new(),
        }
    }

    /// Create an error response.
    pub fn error(status: u16, message: &str) -> Self {
        Self {
            status,
            headers: HashMap::new(),
            body: message.as_bytes().to_vec(),
        }
    }
}

/// Edge compute executor.
#[derive(Clone, Debug)]
pub struct EdgeCompute {
    /// Compute endpoint URL.
    endpoint: String,
    /// Default timeout.
    default_timeout: Duration,
    /// Enabled flag.
    enabled: bool,
}

impl EdgeCompute {
    /// Create a new edge compute executor.
    pub fn new(endpoint: &str) -> Self {
        Self {
            endpoint: endpoint.to_string(),
            default_timeout: Duration::from_secs(10),
            enabled: true,
        }
    }

    /// Create a disabled edge compute (local execution only).
    pub fn disabled() -> Self {
        Self {
            endpoint: String::new(),
            default_timeout: Duration::from_secs(10),
            enabled: false,
        }
    }

    /// Check if edge compute is enabled.
    pub fn is_enabled(&self) -> bool {
        self.enabled
    }

    /// Get the compute endpoint URL.
    pub fn endpoint(&self) -> &str {
        &self.endpoint
    }

    /// Get the default timeout duration.
    pub fn default_timeout(&self) -> Duration {
        self.default_timeout
    }

    /// Set a custom timeout duration.
    pub fn with_timeout(mut self, timeout: Duration) -> Self {
        self.default_timeout = timeout;
        self
    }

    /// Execute an edge function.
    pub async fn execute(
        &self,
        config: &EdgeFunctionConfig,
        _request: EdgeRequest,
    ) -> Result<EdgeResponse, EdgeError> {
        if !self.enabled {
            return Err(EdgeError::NotEnabled);
        }

        // In a full implementation, this would:
        // 1. Route to the nearest compute node
        // 2. Load the function bytecode from storage
        // 3. Execute in a sandboxed environment
        // 4. Return the response

        // For now, return a stub response
        Ok(EdgeResponse::ok(format!(
            "Edge function '{}' executed",
            config.name
        )))
    }

    /// Execute image optimization.
    pub async fn optimize_image(
        &self,
        image_data: &[u8],
        _options: ImageOptimizeOptions,
    ) -> Result<Vec<u8>, EdgeError> {
        if !self.enabled {
            return Err(EdgeError::NotEnabled);
        }

        // In a full implementation, this would use compute nodes for:
        // - Image resizing
        // - Format conversion (WebP, AVIF)
        // - Quality optimization
        // - Face/object detection for smart cropping

        Ok(image_data.to_vec()) // Stub: return original
    }

    /// Run AI inference at the edge.
    pub async fn inference(
        &self,
        _model: &str,
        _input: &[u8],
    ) -> Result<Vec<u8>, EdgeError> {
        if !self.enabled {
            return Err(EdgeError::NotEnabled);
        }

        // In a full implementation, this would:
        // 1. Route to a compute node with the model loaded
        // 2. Use NPU/GPU for inference
        // 3. Return the results

        Ok(Vec::new()) // Stub
    }
}

impl Default for EdgeCompute {
    fn default() -> Self {
        Self::disabled()
    }
}

/// Image optimization options.
#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct ImageOptimizeOptions {
    /// Target width.
    pub width: Option<u32>,
    /// Target height.
    pub height: Option<u32>,
    /// Output format.
    pub format: ImageFormat,
    /// Quality (0-100).
    pub quality: u8,
    /// Fit mode.
    pub fit: ImageFit,
}

impl Default for ImageOptimizeOptions {
    fn default() -> Self {
        Self {
            width: None,
            height: None,
            format: ImageFormat::Auto,
            quality: 80,
            fit: ImageFit::Cover,
        }
    }
}

/// Image output formats.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub enum ImageFormat {
    /// Auto-detect best format.
    Auto,
    /// WebP.
    WebP,
    /// AVIF.
    Avif,
    /// JPEG.
    Jpeg,
    /// PNG.
    Png,
}

/// Image fit modes.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub enum ImageFit {
    /// Cover the area (crop if needed).
    Cover,
    /// Contain within area (letterbox if needed).
    Contain,
    /// Fill the area (stretch if needed).
    Fill,
    /// No resizing, just format conversion.
    None,
}

/// Edge compute errors.
#[derive(Clone, Debug)]
pub enum EdgeError {
    /// Edge compute not enabled.
    NotEnabled,
    /// Timeout.
    Timeout,
    /// Function not found.
    FunctionNotFound(String),
    /// Runtime error.
    RuntimeError(String),
    /// Out of memory.
    OutOfMemory,
    /// Invalid input.
    InvalidInput(String),
}

impl std::fmt::Display for EdgeError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            EdgeError::NotEnabled => write!(f, "Edge compute not enabled"),
            EdgeError::Timeout => write!(f, "Function execution timed out"),
            EdgeError::FunctionNotFound(name) => write!(f, "Function not found: {}", name),
            EdgeError::RuntimeError(msg) => write!(f, "Runtime error: {}", msg),
            EdgeError::OutOfMemory => write!(f, "Out of memory"),
            EdgeError::InvalidInput(msg) => write!(f, "Invalid input: {}", msg),
        }
    }
}

impl std::error::Error for EdgeError {}

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

    #[test]
    fn test_edge_response() {
        let resp = EdgeResponse::ok(b"Hello, World!".to_vec());
        assert_eq!(resp.status, 200);
        assert_eq!(resp.body, b"Hello, World!");

        let redirect = EdgeResponse::redirect("/new-path", false);
        assert_eq!(redirect.status, 302);
        assert_eq!(
            redirect.headers.get("Location"),
            Some(&"/new-path".to_string())
        );

        let error = EdgeResponse::error(404, "Not Found");
        assert_eq!(error.status, 404);
    }

    #[test]
    fn test_edge_function_config() {
        let config = EdgeFunctionConfig {
            name: "api/hello".to_string(),
            runtime: EdgeRuntime::Wasm,
            memory_mb: 256,
            timeout_secs: 30,
            ..Default::default()
        };

        assert_eq!(config.name, "api/hello");
        assert_eq!(config.memory_mb, 256);
    }

    #[tokio::test]
    async fn test_edge_compute_disabled() {
        let compute = EdgeCompute::disabled();
        assert!(!compute.is_enabled());

        let config = EdgeFunctionConfig::default();
        let request = EdgeRequest {
            method: "GET".to_string(),
            path: "/api/test".to_string(),
            query: HashMap::new(),
            headers: HashMap::new(),
            body: None,
            client_ip: None,
            geo: None,
        };

        let result = compute.execute(&config, request).await;
        assert!(matches!(result, Err(EdgeError::NotEnabled)));
    }
}
