package fjord

import "base:runtime"
import "core:bufio"
import "core:bytes"
import "core:io"
import "core:log"
import "core:net"
import "core:path/slashpath"
import "core:strconv"
import "core:strings"
import "core:sync"
import "core:thread"
import "core:unicode"

import http "http"

Server :: struct($Error_Type: typeid) {
    endpoint:          net.Endpoint,
    not_found_handler: #type proc(
        request: ^http.Request,
    ) -> (
        http.Response,
        Error_Type,
    ),
    shutdown:          bool,
    router:            Router(Error_Type),
    work_queue:        WorkQueue,
    worker_count:      int,
    worker_threads:    [dynamic]^thread.Thread,
}

@(private)
read_connection :: proc(
    client_socket: net.TCP_Socket,
    allocator := context.temp_allocator,
) -> (
    data: []byte,
    err: http.RequestError,
) {
    TCP_CHUNK_SIZE :: 1024
    HTTP_END_SEQUENCE :: []byte{'\r', '\n', '\r', '\n'}

    buffer: bytes.Buffer
    bytes.buffer_init_allocator(&buffer, 0, 0, allocator)

    chunk: [TCP_CHUNK_SIZE]byte
    for {
        bytes_read, net_err := net.recv_tcp(client_socket, chunk[:])
        if net_err != nil do return data, .NetworkError

        if bytes_read == 0 do break

        prev_len := len(buffer.buf)
        bytes.buffer_write(&buffer, chunk[:bytes_read])

        search_start := max(0, prev_len - 3)
        if bytes.index(buffer.buf[search_start:], HTTP_END_SEQUENCE) != -1 do break
    }

    return buffer.buf[:], nil
}

server_init :: proc(
    server: ^Server($Error_Type),
    endpoint: net.Endpoint,
    allocator := context.allocator,
) {
    WORKER_COUNT :: 8
    QUEUE_CAPACITY :: 252

    server^ = Server(Error_Type) {
        endpoint = endpoint,
        not_found_handler = proc(
            request: ^http.Request,
        ) -> (
            http.Response,
            Error_Type,
        ) {
            body := "<div>Not found</div>"
            http_response := http.make_response(
                .NotFound,
                transmute([]byte)body,
                .Html,
            )
            return http_response, nil
        },
        shutdown = false,
        worker_count = WORKER_COUNT,
        worker_threads = make([dynamic]^thread.Thread, 0, WORKER_COUNT, allocator),
    }

    work_queue_init(&server.work_queue, QUEUE_CAPACITY, allocator)
    router_init(&server.router, allocator)
}

server_destroy :: proc(server: ^Server($Error_Type)) {
    for t in server.worker_threads {
        thread.destroy(t)
    }
    delete(server.worker_threads)
    work_queue_destroy(&server.work_queue)
    router_destroy(&server.router)
}

// This is used instead of default server_make param until compiler bug is fixed: https://github.com/odin-lang/Odin/issues/5792
server_set_not_found_handler :: proc(
    server: ^Server($Error_Type),
    not_found_handler: #type proc(
        request: ^http.Request,
    ) -> (
        http.Response,
        Error_Type,
    ),
) {
    server.not_found_handler = not_found_handler
}

server_add_route :: proc(
    server: ^Server($Error_Type),
    method: http.Method,
    path: []string,
    handler: #type proc(request: ^http.Request) -> (http.Response, Error_Type),
) {
    router_add_route(&server.router, method, path, handler)
}

server_remove_route :: proc(
    server: ^Server($Error_Type),
    method: http.Method,
    path: []string,
) -> (
    ok: bool,
) {
    return router_remove_route(&server.router, method, path)
}

server_shutdown :: proc(server: ^Server($Error_Type)) {
    sync.atomic_store(&server.shutdown, true)
}

@(private)
serve :: proc(server: ^Server($Error_Type), client_socket: net.TCP_Socket) {
    data, read_err := read_connection(client_socket, context.temp_allocator)
    if read_err != nil {
        log.warnf("Failed to read request, reason: %s", read_err)
        return
    }

    http_request, unmarshall_err := http.unmarshall_request(
        data,
        context.temp_allocator,
    )
    if unmarshall_err != nil {
        log.warnf("Failed to unmarshall request, reason: %s", unmarshall_err)
        return
    }

    handler: #type proc(request: ^http.Request) -> (http.Response, Error_Type)
    ok: bool

    // todo: should sanitize better
    path := strings.split(http_request.path, "/", context.temp_allocator)[1:]

    handler, http_request.path_variables, ok = router_lookup(
        &server.router,
        http_request.method,
        path,
        context.temp_allocator,
    )
    if !ok do handler = server.not_found_handler

    http_response, handler_err := handler(&http_request)

    if handler_err != nil {
        log.warnf("Handler failed with error: %s", handler_err)
        return
    }

    marshalled_response := http.marshall_response(
        &http_response,
        context.temp_allocator,
    )
    net.send_tcp(client_socket, marshalled_response)
}

@(private)
worker_thread :: proc(server: ^Server($Error_Type)) {
    for {
        socket, ok := work_queue_dequeue(&server.work_queue)
        if !ok do break

        serve(server, socket)
        net.close(socket)
        free_all(context.temp_allocator)
    }
}

server_listen_and_serve :: proc(server: ^Server($Error_Type)) {
    server_socket, net_err := net.listen_tcp(server.endpoint)
    log.assert(net_err == nil, "Couldn't create TCP socket")
    defer net.close(server_socket)

    for i in 0 ..< server.worker_count {
        t := thread.create(proc(t: ^thread.Thread) {
            server := cast(^Server(Error_Type))t.data
            worker_thread(server)
        })
        log.assertf(t != nil, "Thread creation failed")

        t.data = rawptr(server)
        thread.start(t)
        append(&server.worker_threads, t)
    }

    for !sync.atomic_load(&server.shutdown) {
        client_socket, _, net_err := net.accept_tcp(server_socket)
        if net_err != nil {
            log.warnf("Failed to accept TCP connection, reason: %s", net_err)
            continue
        }

        ok := work_queue_enqueue(&server.work_queue, client_socket)
        if !ok {
            log.warn("Work queue full, rejecting connection")
            net.close(client_socket)
        }
    }

    work_queue_shutdown(&server.work_queue)

    for t in server.worker_threads {
        thread.join(t)
    }
}