package http

import "core:bufio"
import "core:bytes"
import "core:io"
import "core:log"
import "core:net"
import "core:strconv"
import "core:strings"
import "core:unicode"

@(private)
method_from_str :: proc(method_str: string) -> Method {
    switch method_str {
    case "GET":
        return .GET
    case "DELETE":
        return .DELETE
    case "PUT":
        return .PUT
    case "POST":
        return .POST
    }
    unreachable()
}

@(private)
str_from_content_type :: proc(content_type: ContentType) -> string {
    switch content_type {
    case .Html:
        return "text/html"
    case .Image:
        return "image/jpeg"
    }
    unreachable()
}

@(private)
status_text :: proc(status: Status) -> string {
    switch status {
    case .Ok:
        return "OK"
    case .NotFound:
        return "Not found"
    case .BadRequest:
        return "Bad request"
    case .InternalServerError:
        return "Internal server error"
    }

    unreachable()
}

@(private)
unmarshall_request_line :: proc(
    request: ^Request,
    reader: ^bufio.Reader,
    allocator := context.temp_allocator
) -> RequestError {
    request_line, io_err := bufio.reader_read_slice(reader, '\n')
    if io_err != nil do return .InvalidRequestLine

    request_line = sanitize_byte_slice(request_line)

    parts := bytes.split(request_line, {' '}, allocator)
    if len(parts) != 3 do return .InvalidRequestLine

    request.method = method_from_str(string(parts[0]))
    request.path = string(parts[1])
    request.proto_version = string(parts[2])

    return nil
}

@(private)
unmarshall_request_headers :: proc(
    request: ^Request,
    reader: ^bufio.Reader,
    allocator := context.temp_allocator,
) -> RequestError {
    request.header = make(Header, allocator)

    for {
        header_line, io_err := bufio.reader_read_slice(reader, '\n')
        if io_err != nil do return .InvalidHeaderFormat

        header_line = sanitize_byte_slice(header_line)
        if len(header_line) == 0 do break

        parts := bytes.split_n(header_line, {':'}, 2, allocator)
        if len(parts) != 2 do return .InvalidHeaderFormat

        key := string(bytes.trim_space(parts[0]))
        value := string(bytes.trim_space(parts[1]))

        request.header[key] = value
    }

    return nil
}

@(private)
unmarshall_request_body :: proc(
    request: ^Request,
    reader: ^bufio.Reader,
    allocator := context.temp_allocator,
) -> RequestError {
    content_length_str, ok := request.header["Content-Length"]

    if ok {
        content_length, ok := strconv.parse_uint(content_length_str)
        if !ok do return .InvalidHeaderFormat
        request.body = make([]byte, content_length, allocator)

        _, err := bufio.reader_read(reader, request.body)
        if err != nil do return .FailedParsing

    } else {
        request.body = {}
    }

    return nil
}

@(private)
sanitize_byte_slice :: proc(slice: []byte) -> []byte {
    return bytes.trim(slice, {'\n', '\r'})
}

unmarshall_request :: proc(
    data: []byte,
    allocator := context.temp_allocator,
) -> (
    request: Request,
    request_err: RequestError,
) {
    if len(data) == 0 do return request, .IncompleteRequest

    byte_reader: bytes.Reader
    stream := bytes.reader_init(&byte_reader, data)

    reader: bufio.Reader
    bufio.reader_init(&reader, io.to_reader(stream), allocator = allocator)
    defer bufio.reader_destroy(&reader)

    unmarshall_request_line(&request, &reader) or_return
    unmarshall_request_headers(&request, &reader, allocator) or_return
    unmarshall_request_body(&request, &reader, allocator) or_return

    return request, nil
}

marshall_response :: proc(
    response: ^Response,
    allocator := context.temp_allocator,
) -> []byte {
    buffer: bytes.Buffer
    bytes.buffer_init_allocator(&buffer, 0, 0, allocator)

    bytes.buffer_write_string(&buffer, response.proto_version)
    bytes.buffer_write_string(&buffer, " ")

    status_code_buf := make([]byte, 4, allocator)
    status_code_str := strconv.write_uint(
        status_code_buf[:],
        u64(response.status),
        10,
    )

    bytes.buffer_write_string(&buffer, status_code_str)
    bytes.buffer_write_string(&buffer, " ")

    status_msg := status_text(response.status)
    bytes.buffer_write_string(&buffer, status_msg)
    bytes.buffer_write_string(&buffer, "\r\n")

    for key, value in response.header {
        bytes.buffer_write_string(&buffer, key)
        bytes.buffer_write_string(&buffer, ": ")
        bytes.buffer_write_string(&buffer, value)
        bytes.buffer_write_string(&buffer, "\r\n")
    }

    bytes.buffer_write_string(&buffer, "\r\n")

    bytes.buffer_write(&buffer, response.body)

    return bytes.buffer_to_bytes(&buffer)
}