#!/bin/env tomo

# This file provides an HTTP server module and standalone executable

use <stdio.h>
use <stdlib.h>
use <string.h>
use <unistd.h>
use <arpa/inet.h>
use <err.h>

use commands
use pthreads
use patterns

use ./connection-queue.tm

func serve(port:Int32, handler:func(request:HTTPRequest -> HTTPResponse), num_threads=16):
    connections := ConnectionQueue()
    workers := &[:@pthread_t] 
    for i in num_threads:
        workers:insert(pthread_t.new(func():
            repeat:
                connection := connections:dequeue()
                request_text := inline C : Text {
                    Text_t request = EMPTY_TEXT;
                    char buf[1024] = {};
                    for (ssize_t n; (n = read(_$connection, buf, sizeof(buf) - 1)) > 0; ) {
                        buf[n] = 0;
                        request = Text$concat(request, Text$from_strn(buf, n));
                        if (request.length > 1000000 || strstr(buf, "\r\n\r\n"))
                            break;
                    }
                    request
                }

                request := HTTPRequest.from_text(request_text) or skip
                response := handler(request):bytes()
                inline C {
                    if (_$response.stride != 1)
                        Array$compact(&_$response, 1);
                    write(_$connection, _$response.data, _$response.length);
                    close(_$connection);
                }
        ))


    sock := inline C : Int32 {
        int s = socket(AF_INET, SOCK_STREAM, 0);
        if (s < 0) err(1, "Couldn't connect to socket!");

        int opt = 1;
        if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) < 0)
            err(1, "Couldn't set socket option");
            
        struct sockaddr_in addr = {AF_INET, htons(_$port), INADDR_ANY};
        if (bind(s, (struct sockaddr*)&addr, sizeof(addr)) < 0)
            err(1, "Couldn't bind to socket");
        if (listen(s, 8) < 0)
            err(1, "Couldn't listen on socket");

        s
    }

    repeat:
        conn := inline C : Int32 { accept(_$sock, NULL, NULL) }
        stop if conn < 0 
        connections:enqueue(conn)

    say("Shutting down...")
    for w in workers:
        w:cancel()

struct HTTPRequest(method:Text, path:Text, version:Text, headers:[Text], body:Text):
    func from_text(text:Text -> HTTPRequest?):
        m := text:pattern_captures($Pat'{word} {..} HTTP/{..}{crlf}{..}') or return none
        method := m[1]
        path := m[2]:replace_pattern($Pat'{2+ /}', '/')
        version := m[3]
        rest := m[-1]:pattern_captures($Pat/{..}{2 crlf}{0+ ..}/) or return none
        headers := rest[1]:split_pattern($Pat/{crlf}/)
        body := rest[-1]
        return HTTPRequest(method, path, version, headers, body)

struct HTTPResponse(body:Text, status=200, content_type="text/plain", headers={:Text=Text}):
    func bytes(r:HTTPResponse -> [Byte]):
        body_bytes := r.body:bytes()
        extra_headers := (++: "$k: $v$(\r\n)" for k,v in r.headers) or ""
        return "
            HTTP/1.1 $(r.status) OK$\r
            Content-Length: $(body_bytes.length + 2)$\r
            Content-Type: $(r.content_type)$\r
            Connection: close$\r
            $extra_headers
            $\r$\n
        ":bytes() ++ body_bytes

func _content_type(file:Path -> Text):
    when file:extension() is "html": return "text/html"
    is "tm": return "text/html"
    is "js": return "text/javascript"
    is "css": return "text/css"
    else: return "text/plain"

enum RouteEntry(ServeFile(file:Path), Redirect(destination:Text)):
    func respond(entry:RouteEntry, request:HTTPRequest -> HTTPResponse):
        when entry is ServeFile(file):
            body := if file:can_execute():
                Command(Text(file)):get_output()!
            else:
                file:read()!
            return HTTPResponse(body, content_type=_content_type(file))
        is Redirect(destination):
            return HTTPResponse("Found", 302, headers={"Location"=destination})

func load_routes(directory:Path -> {Text=RouteEntry}):
    routes := &{:Text=RouteEntry}
    for file in (directory ++ (./*)):glob():
        skip unless file:is_file()
        contents := file:read() or skip
        server_path := "/" ++ "/":join(file:relative_to(directory).components)
        if file:base_name() == "index.html":
            canonical := server_path:without_suffix("index.html")
            routes[server_path] = Redirect(canonical)
            routes[canonical] = ServeFile(file)
        else if file:extension() == "html":
            canonical := server_path:without_suffix(".html")
            routes[server_path] = Redirect(canonical)
            routes[canonical] = ServeFile(file)
        else if file:extension() == "tm":
            canonical := server_path:without_suffix(".tm")
            routes[server_path] = Redirect(canonical)
            routes[canonical] = ServeFile(file)
        else:
            routes[server_path] = ServeFile(file)
    return routes[]

func main(directory:Path, port=Int32(8080)):
    say("Serving on port $port")
    routes := load_routes(directory)
    !! Hosting: $routes

    serve(port, func(request:HTTPRequest):
        if handler := routes[request.path]:
            return handler:respond(request)
        else:
            return HTTPResponse("Not found!", 404)
    )