// Copyright (c) 2019-2024 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module http

import net

const vschannel_connect_failed_msg = 'Failed to connect to host'

const vschannel_sec_e_internal_error = -2146893052

// A fast version that avoids allocations in s.split()
// returns the locations of the 2 spaces
// "GET / HTTP/1.1" => ["GET" "/" "HTTP/1.1"]
fn fast_request_words(line string) (int, int) {
    space1 := line.index(' ') or { return 0, 0 }
    space2 := line.index_after(' ', space1 + 1) or { return 0, 0 }
    return space1, space2
}

fn vschannel_error_message(err_code int) string {
    $if windows {
        if err_code >= int(net.WsaError.wsaeintr)
            && err_code <= int(net.WsaError.wsa_ipsec_name_policy_error) {
            return '(${err_code}) ${net.wsa_error(err_code)}'
        }
    }
    if err_code < 0 {
        return '0x${u32(err_code):08x}'
    }
    return '${err_code}'
}

fn vschannel_connect_error(err_code int) IError {
    if err_code == 0 {
        return error(vschannel_connect_failed_msg)
    }
    return error_with_code(vschannel_connect_failed_msg, err_code)
}

fn vschannel_should_report_connect_failure(err_code int) bool {
    if err_code == vschannel_sec_e_internal_error {
        return true
    }
    $if windows {
        return err_code in [int(net.WsaError.wsaenotconn), int(net.WsaError.wsaenetdown),
            int(net.WsaError.wsaenetunreach), int(net.WsaError.wsaetimedout),
            int(net.WsaError.wsaeconnrefused), int(net.WsaError.wsaehostdown),
            int(net.WsaError.wsaehostunreach), int(net.WsaError.wsahost_not_found),
            int(net.WsaError.wsatry_again), int(net.WsaError.wsano_recovery),
            int(net.WsaError.wsano_data)]
    }
    return false
}

fn vschannel_looks_like_connect_failure_response(response_text string) bool {
    trimmed := response_text.trim_space()
    return trimmed.starts_with('Error ') && (trimmed.contains('sending data to server')
        || trimmed.contains('Error performing handshake'))
}

fn vschannel_request_error(err_code int) IError {
    if vschannel_should_report_connect_failure(err_code) {
        return vschannel_connect_error(err_code)
    }
    return error_with_code('http: vschannel request failed: ${vschannel_error_message(err_code)}',
        err_code)
}

fn vschannel_parse_response(response_text string, err_code int) !Response {
    if response_text.len < 5 || response_text[..5].to_lower() != 'http/' {
        if vschannel_should_report_connect_failure(err_code)
            || vschannel_looks_like_connect_failure_response(response_text) {
            return vschannel_connect_error(err_code)
        }
    }
    return parse_response(response_text)
}