// SPDX-License-Identifier: MPL-2.0 OR MIT
// Copyright 2024 AffineScript Contributors

//! Package Registry Client
//!
//! Communicates with the AffineScript package registry.

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

/// Default registry URL
pub const DEFAULT_REGISTRY: &str = "https://packages.affinescript.dev";

/// Registry client
pub struct RegistryClient {
    /// HTTP client
    client: reqwest::Client,

    /// Registry base URL
    base_url: String,

    /// Authentication token
    token: Option<String>,
}

/// Package search result
#[derive(Debug, Clone, Deserialize)]
pub struct SearchResult {
    /// Total number of matches
    pub total: usize,

    /// Matching packages
    pub packages: Vec<PackageSummary>,
}

/// Package summary (from search)
#[derive(Debug, Clone, Deserialize)]
pub struct PackageSummary {
    /// Package name
    pub name: String,

    /// Latest version
    pub version: String,

    /// Description
    pub description: Option<String>,

    /// Download count
    pub downloads: u64,
}

/// Full package info
#[derive(Debug, Clone, Deserialize)]
pub struct PackageInfo {
    /// Package name
    pub name: String,

    /// All published versions
    pub versions: Vec<VersionInfo>,

    /// Keywords
    pub keywords: Vec<String>,

    /// Categories
    pub categories: Vec<String>,

    /// Repository URL
    pub repository: Option<String>,

    /// Documentation URL
    pub documentation: Option<String>,

    /// Homepage URL
    pub homepage: Option<String>,
}

/// Version info
#[derive(Debug, Clone, Deserialize)]
pub struct VersionInfo {
    /// Version number
    pub version: String,

    /// Publish date
    pub published_at: String,

    /// Download URL
    pub download_url: String,

    /// SHA-256 checksum
    pub checksum: String,

    /// Dependencies
    pub dependencies: HashMap<String, String>,

    /// Features
    pub features: HashMap<String, Vec<String>>,

    /// Whether this version is yanked
    pub yanked: bool,
}

/// Publish request
#[derive(Debug, Clone, Serialize)]
pub struct PublishRequest {
    /// Package name
    pub name: String,

    /// Version
    pub version: String,

    /// Tarball contents (base64)
    pub tarball: String,

    /// SHA-256 of tarball
    pub checksum: String,
}

/// Registry error
#[derive(Debug, thiserror::Error)]
pub enum RegistryError {
    #[error("HTTP error: {0}")]
    Http(#[from] reqwest::Error),

    #[error("Package not found: {0}")]
    NotFound(String),

    #[error("Authentication required")]
    Unauthorized,

    #[error("Rate limited, retry after {0} seconds")]
    RateLimited(u64),

    #[error("Registry error: {0}")]
    RegistryError(String),
}

impl RegistryClient {
    /// Create a new registry client
    pub fn new(base_url: Option<String>) -> Self {
        RegistryClient {
            client: reqwest::Client::new(),
            base_url: base_url.unwrap_or_else(|| DEFAULT_REGISTRY.to_string()),
            token: None,
        }
    }

    /// Set authentication token
    pub fn with_token(mut self, token: String) -> Self {
        self.token = Some(token);
        self
    }

    /// Search for packages
    pub async fn search(&self, query: &str, page: u32) -> Result<SearchResult, RegistryError> {
        // TODO: Phase 8 implementation
        // GET /api/v1/search?q={query}&page={page}
        let _ = (query, page);
        Ok(SearchResult {
            total: 0,
            packages: vec![],
        })
    }

    /// Get package info
    pub async fn get_package(&self, name: &str) -> Result<PackageInfo, RegistryError> {
        // TODO: Phase 8 implementation
        // GET /api/v1/packages/{name}
        let _ = name;
        Err(RegistryError::NotFound(name.to_string()))
    }

    /// Get specific version info
    pub async fn get_version(
        &self,
        name: &str,
        version: &Version,
    ) -> Result<VersionInfo, RegistryError> {
        // TODO: Phase 8 implementation
        // GET /api/v1/packages/{name}/{version}
        let _ = (name, version);
        Err(RegistryError::NotFound(format!("{}@{}", name, version)))
    }

    /// Download package tarball
    pub async fn download(&self, url: &str) -> Result<bytes::Bytes, RegistryError> {
        // TODO: Phase 8 implementation
        // GET {download_url}
        let _ = url;
        Ok(bytes::Bytes::new())
    }

    /// Publish a package
    pub async fn publish(&self, request: PublishRequest) -> Result<(), RegistryError> {
        // TODO: Phase 8 implementation
        // PUT /api/v1/packages/{name}
        // Authorization: Bearer {token}
        let _ = request;

        if self.token.is_none() {
            return Err(RegistryError::Unauthorized);
        }

        Ok(())
    }

    /// Yank a version
    pub async fn yank(&self, name: &str, version: &Version) -> Result<(), RegistryError> {
        // TODO: Phase 8 implementation
        // DELETE /api/v1/packages/{name}/{version}
        let _ = (name, version);

        if self.token.is_none() {
            return Err(RegistryError::Unauthorized);
        }

        Ok(())
    }

    /// Unyank a version
    pub async fn unyank(&self, name: &str, version: &Version) -> Result<(), RegistryError> {
        // TODO: Phase 8 implementation
        // PUT /api/v1/packages/{name}/{version}/unyank
        let _ = (name, version);

        if self.token.is_none() {
            return Err(RegistryError::Unauthorized);
        }

        Ok(())
    }

    /// Get owners of a package
    pub async fn get_owners(&self, name: &str) -> Result<Vec<String>, RegistryError> {
        // TODO: Phase 8 implementation
        // GET /api/v1/packages/{name}/owners
        let _ = name;
        Ok(vec![])
    }

    /// Add an owner
    pub async fn add_owner(&self, name: &str, user: &str) -> Result<(), RegistryError> {
        // TODO: Phase 8 implementation
        // PUT /api/v1/packages/{name}/owners
        let _ = (name, user);

        if self.token.is_none() {
            return Err(RegistryError::Unauthorized);
        }

        Ok(())
    }
}

// TODO: Phase 8 implementation
// - [ ] Implement actual HTTP requests
// - [ ] Add retry logic with backoff
// - [ ] Add caching with ETags
// - [ ] Add offline mode with cached index
// - [ ] Add sparse index support
// - [ ] Add parallel downloads
