// SPDX-License-Identifier: MIT OR Apache-2.0
// This file is part of Static Web Server.
// See https://static-web-server.net/ for more information
// Copyright (C) 2019-present Jose Quintana <joseluisq.net>

//! Request handler module intended to manage incoming HTTP requests.
//!

use hyper::{Body, Request, Response, StatusCode};
use std::{
    future::Future,
    net::{IpAddr, SocketAddr},
    path::PathBuf,
    sync::Arc,
};

#[cfg(any(
    feature = "compression",
    feature = "compression-gzip",
    feature = "compression-brotli",
    feature = "compression-zstd",
    feature = "compression-deflate"
))]
use crate::compression;

use crate::compression_static;

#[cfg(feature = "basic-auth")]
use crate::basic_auth;

#[cfg(feature = "fallback-page")]
use crate::fallback_page;

#[cfg(feature = "metrics")]
use crate::metrics;

#[cfg(feature = "experimental")]
use crate::mem_cache::cache::MemCacheOpts;

use crate::{
    Error, Result, control_headers, cors, custom_headers, error_page, health,
    http_ext::MethodExt,
    log_addr, maintenance_mode, redirects, rewrites, security_headers,
    settings::Advanced,
    static_files::{self, HandleOpts},
    text_charset, virtual_hosts,
};

#[cfg(feature = "directory-listing")]
use crate::directory_listing::DirListFmt;

#[cfg(feature = "directory-listing-download")]
use crate::directory_listing_download::DirDownloadFmt;

/// It defines options for a request handler.
pub struct RequestHandlerOpts {
    // General options
    /// Root directory of static files.
    pub root_dir: PathBuf,
    #[cfg(feature = "experimental")]
    /// In-memory cache feature (experimental).
    pub memory_cache: Option<MemCacheOpts>,
    /// Compression feature.
    pub compression: bool,
    #[cfg(any(
        feature = "compression",
        feature = "compression-gzip",
        feature = "compression-brotli",
        feature = "compression-zstd",
        feature = "compression-deflate"
    ))]
    /// Compression level.
    pub compression_level: crate::settings::CompressionLevel,
    /// Compression static feature.
    pub compression_static: bool,
    /// Directory listing feature.
    #[cfg(feature = "directory-listing")]
    #[cfg_attr(docsrs, doc(cfg(feature = "directory-listing")))]
    pub dir_listing: bool,
    /// Directory listing order feature.
    #[cfg(feature = "directory-listing")]
    #[cfg_attr(docsrs, doc(cfg(feature = "directory-listing")))]
    pub dir_listing_order: u8,
    #[cfg(feature = "directory-listing")]
    #[cfg_attr(docsrs, doc(cfg(feature = "directory-listing")))]
    /// Directory listing format feature.
    pub dir_listing_format: DirListFmt,
    /// Directory listing download feature.
    #[cfg(feature = "directory-listing-download")]
    #[cfg_attr(docsrs, doc(cfg(feature = "directory-listing-download")))]
    pub dir_listing_download: Vec<DirDownloadFmt>,
    /// CORS feature.
    pub cors: Option<cors::Configured>,
    /// Security headers feature.
    pub security_headers: bool,
    /// Cache control headers feature.
    pub cache_control_headers: bool,
    /// Page for 404 errors.
    pub page404: PathBuf,
    /// Page for 50x errors.
    pub page50x: PathBuf,
    /// Page fallback feature.
    #[cfg(feature = "fallback-page")]
    #[cfg_attr(docsrs, doc(cfg(feature = "fallback-page")))]
    pub page_fallback: Vec<u8>,
    /// Basic auth feature.
    #[cfg(feature = "basic-auth")]
    #[cfg_attr(docsrs, doc(cfg(feature = "basic-auth")))]
    pub basic_auth: String,
    /// Index files feature.
    pub index_files: Vec<String>,
    /// Log remote address feature.
    pub log_remote_address: bool,
    /// Log the X-Real-IP header.
    pub log_x_real_ip: bool,
    /// Log the X-Forwarded-For header.
    pub log_forwarded_for: bool,
    /// Trusted IPs for remote addresses.
    pub trusted_proxies: Vec<IpAddr>,
    /// Redirect trailing slash feature.
    pub redirect_trailing_slash: bool,
    /// Ignore hidden files feature.
    pub ignore_hidden_files: bool,
    /// Prevent following symlinks for files and directories.
    pub disable_symlinks: bool,
    /// Resolve the web root directory at request time rather than at startup.
    pub use_relative_root: bool,
    /// Accept markdown content negotiation feature.
    pub accept_markdown: bool,
    /// Default `charset=utf-8` parameter applied to certain `text` responses without one.
    pub text_charset: bool,
    /// Health endpoint feature.
    pub health: bool,
    /// Metrics endpoint feature.
    #[cfg(feature = "metrics")]
    pub metrics_enabled: bool,
    /// Maintenance mode feature.
    pub maintenance_mode: bool,
    /// Custom HTTP status for when entering into maintenance mode.
    pub maintenance_mode_status: StatusCode,
    /// Custom maintenance mode HTML file.
    pub maintenance_mode_file: PathBuf,

    /// Advanced options from the config file.
    pub advanced_opts: Option<Advanced>,
}

impl Default for RequestHandlerOpts {
    fn default() -> Self {
        Self {
            root_dir: PathBuf::from("./public"),
            compression: true,
            compression_static: false,
            #[cfg(any(
                feature = "compression",
                feature = "compression-gzip",
                feature = "compression-brotli",
                feature = "compression-zstd",
                feature = "compression-deflate"
            ))]
            compression_level: crate::settings::CompressionLevel::Default,
            #[cfg(feature = "directory-listing")]
            dir_listing: false,
            #[cfg(feature = "directory-listing")]
            dir_listing_order: 6, // unordered
            #[cfg(feature = "directory-listing")]
            dir_listing_format: DirListFmt::Html,
            #[cfg(feature = "directory-listing-download")]
            dir_listing_download: Vec::new(),
            cors: None,
            #[cfg(feature = "experimental")]
            memory_cache: None,
            security_headers: false,
            cache_control_headers: true,
            page404: PathBuf::from("./404.html"),
            page50x: PathBuf::from("./50x.html"),
            #[cfg(feature = "fallback-page")]
            page_fallback: Vec::new(),
            #[cfg(feature = "basic-auth")]
            basic_auth: String::new(),
            index_files: vec!["index.html".into()],
            log_remote_address: false,
            log_x_real_ip: false,
            log_forwarded_for: false,
            trusted_proxies: Vec::new(),
            redirect_trailing_slash: true,
            ignore_hidden_files: false,
            disable_symlinks: false,
            use_relative_root: false,
            accept_markdown: false,
            text_charset: true,
            health: false,
            #[cfg(feature = "metrics")]
            metrics_enabled: false,
            maintenance_mode: false,
            maintenance_mode_status: StatusCode::SERVICE_UNAVAILABLE,
            maintenance_mode_file: PathBuf::new(),
            advanced_opts: None,
        }
    }
}

/// It defines the main request handler used by the Hyper service request.
pub struct RequestHandler {
    /// Request handler options.
    pub opts: Arc<RequestHandlerOpts>,
}

impl RequestHandler {
    /// Main entry point for incoming requests.
    pub fn handle<'a>(
        &'a self,
        req: &'a mut Request<Body>,
        remote_addr: Option<SocketAddr>,
    ) -> impl Future<Output = Result<Response<Body>, Error>> + Send + 'a {
        let mut base_path = &self.opts.root_dir;
        #[cfg(feature = "directory-listing")]
        let dir_listing = self.opts.dir_listing;
        #[cfg(feature = "directory-listing")]
        let dir_listing_order = self.opts.dir_listing_order;
        #[cfg(feature = "directory-listing")]
        let dir_listing_format = &self.opts.dir_listing_format;
        #[cfg(feature = "directory-listing-download")]
        let dir_listing_download = &self.opts.dir_listing_download;
        let redirect_trailing_slash = self.opts.redirect_trailing_slash;
        let compression_static = self.opts.compression_static;
        let ignore_hidden_files = self.opts.ignore_hidden_files;
        let disable_symlinks = self.opts.disable_symlinks;
        let index_files: Vec<&str> = self.opts.index_files.iter().map(|s| s.as_str()).collect();
        #[cfg(feature = "experimental")]
        let memory_cache = self.opts.memory_cache.as_ref();

        log_addr::pre_process(&self.opts, req, remote_addr);

        async move {
            #[cfg(feature = "metrics")]
            let req_start = std::time::Instant::now();
            #[cfg(feature = "metrics")]
            let metrics_enabled = self.opts.metrics_enabled;

            #[cfg(feature = "metrics")]
            if metrics_enabled {
                metrics::inc_requests_inflight();
            }

            let result: Result<Response<Body>, Error> = async {
                // Reject if the HTTP request method is not allowed
                if !req.method().is_allowed() {
                    return error_page::error_response(
                        req.uri(),
                        req.method(),
                        &StatusCode::METHOD_NOT_ALLOWED,
                        &self.opts.page404,
                        &self.opts.page50x,
                    );
                }

                // Health endpoint check
                if let Some(result) = health::pre_process(&self.opts, req) {
                    return result;
                }

                // CORS
                if let Some(result) = cors::pre_process(&self.opts, req) {
                    return result;
                }

                // `Basic` HTTP Authorization Schema
                #[cfg(feature = "basic-auth")]
                if let Some(response) = basic_auth::pre_process(&self.opts, req) {
                    return response;
                }

                // Metrics endpoint check
                #[cfg(feature = "metrics")]
                if let Some(result) = metrics::pre_process(&self.opts, req) {
                    return result;
                }

                // Maintenance Mode
                if let Some(response) = maintenance_mode::pre_process(&self.opts, req) {
                    return response;
                }

                // Redirects
                if let Some(result) = redirects::pre_process(&self.opts, req) {
                    return result;
                }

                // Rewrites
                if let Some(result) = rewrites::pre_process(&self.opts, req) {
                    return result;
                }

                // Advanced options
                if let Some(advanced) = &self.opts.advanced_opts {
                    // If the "Host" header matches any virtual_host, change the root directory
                    if let Some(root) =
                        virtual_hosts::get_real_root(req, advanced.virtual_hosts.as_deref())
                    {
                        base_path = root;
                    }
                }

                let index_files = index_files.as_ref();

                // Check for markdown content negotiation (only if enabled)
                let uri_path_md = if self.opts.accept_markdown {
                    crate::markdown::pre_process(
                        req,
                        base_path,
                        req.uri().path(),
                        self.opts.ignore_hidden_files,
                    )
                } else {
                    None
                };
                let uri_path = uri_path_md.as_deref().unwrap_or(req.uri().path());

                // Static files
                let (resp, file_path) = match static_files::handle(&HandleOpts {
                    method: req.method(),
                    headers: req.headers(),
                    #[cfg(feature = "experimental")]
                    memory_cache,
                    base_path,
                    uri_path,
                    uri_query: req.uri().query(),
                    #[cfg(feature = "directory-listing")]
                    dir_listing,
                    #[cfg(feature = "directory-listing")]
                    dir_listing_order,
                    #[cfg(feature = "directory-listing")]
                    dir_listing_format,
                    #[cfg(feature = "directory-listing-download")]
                    dir_listing_download,
                    redirect_trailing_slash,
                    compression_static,
                    ignore_hidden_files,
                    index_files,
                    disable_symlinks,
                })
                .await
                {
                    Ok(result) => (result.resp, Some(result.file_path)),
                    Err(status) => (
                        error_page::error_response(
                            req.uri(),
                            req.method(),
                            &status,
                            &self.opts.page404,
                            &self.opts.page50x,
                        )?,
                        None,
                    ),
                };

                // Check for a fallback response
                #[cfg(feature = "fallback-page")]
                let resp = fallback_page::post_process(&self.opts, req, resp)?;

                // Append CORS headers if they are present
                let resp = cors::post_process(&self.opts, req, resp)?;

                // Set Content-Type for markdown files
                let resp = crate::markdown::post_process(uri_path_md.is_some(), &self.opts, resp)?;

                // Declare a default charset for `text/*` responses
                let resp = text_charset::post_process(&self.opts, resp)?;

                // Add a `Vary` header if static compression is used
                let resp = compression_static::post_process(&self.opts, req, resp)?;

                // Auto compression based on the `Accept-Encoding` header
                #[cfg(any(
                    feature = "compression",
                    feature = "compression-gzip",
                    feature = "compression-brotli",
                    feature = "compression-zstd",
                    feature = "compression-deflate"
                ))]
                let resp = compression::post_process(&self.opts, req, resp)?;

                // Append `Cache-Control` headers for web assets
                let resp = control_headers::post_process(&self.opts, req, resp)?;

                // Append security headers
                let resp = security_headers::post_process(&self.opts, req, resp)?;

                // Add/update custom headers
                let resp = custom_headers::post_process(&self.opts, req, resp, file_path.as_ref())?;

                Ok(resp)
            }
            .await;

            #[cfg(feature = "metrics")]
            if metrics_enabled {
                metrics::dec_requests_inflight();
                if let Ok(ref resp) = result {
                    let bytes = resp
                        .headers()
                        .get(hyper::header::CONTENT_LENGTH)
                        .and_then(|v| v.to_str().ok())
                        .and_then(|v| v.parse::<u64>().ok())
                        .unwrap_or(0);
                    metrics::record_request(
                        req,
                        resp.status(),
                        bytes,
                        req_start.elapsed().as_secs_f64(),
                    );
                }
            }

            result
        }
    }
}
