package main

import (

"os"

"regexp"

"strings"

)

// parseAdditionalHeaders reads the environment for values like SRC_HEADER_NAME=VALUE or

// SRC_HEADERS and creates a `{NAME: VALUE}` map. These headers should be applied to each

// request to the Sourcegraph instance, as some private instances require special auth or

// additional proxy values to be passed along with each request.

func parseAdditionalHeaders() map[string]string {

return parseAdditionalHeadersFromEnviron(os.Environ())

}

const additionalHeaderPrefix = "SRC_HEADER_"

const additionalHeadersKey = "SRC_HEADERS"

func parseAdditionalHeadersFromEnviron(environ []string) map[string]string {

additionalHeaders := map[string]string{}

for _, value := range environ {

parts := strings.SplitN(value, "=", 2)

if len(parts) != 2 {

continue

}

if parts[0] == additionalHeadersKey && parts[1] != "" {

// This regex removes all leading and trailing spaces from the environment variable. We need to do this

// because most shells add quotes to a string when it contains a new line. Tested with `bash, fish & zsh`

// and they all have the same behavior.

re := regexp.MustCompile(`^"|"$`)

headers := re.ReplaceAllString(parts[1], "")

// Most shell convert line breaks added to a string, so we need to replace all occurence of the stringified line

// breaks to actual line breaks.

headers = strings.ReplaceAll(headers, `\n`, "\n")

splitHeaders := strings.SplitSeq(headers, "\n")

for h := range splitHeaders {

p := strings.SplitN(h, ":", 2)

if len(p) != 2 || p[1] == "" {

continue

}

key := strings.Trim(strings.ToLower(p[0]), " ")

value := strings.Trim(p[1], " ")

additionalHeaders[key] = value

}

continue

}

// Ensure we'll have a non-empty key after trimming

if !strings.HasPrefix(parts[0], additionalHeaderPrefix) || len(parts[0]) <= len(additionalHeaderPrefix) {

continue

}

// Ensure we have a non-empty value

if parts[1] == "" {

continue

}

additionalHeaders[strings.ToLower(strings.TrimPrefix(parts[0], additionalHeaderPrefix))] = parts[1]

}

return additionalHeaders

}