export * as ConfigVariable from "./variable"

import path from "path"

import os from "os"

import { Filesystem } from "@/util"

import { InvalidError } from "./error"

type ParseSource =

| {

type: "path"

path: string

}

| {

type: "virtual"

source: string

dir: string

}

type SubstituteInput = ParseSource & {

text: string

missing?: "error" | "empty"

}

function source(input: ParseSource) {

return input.type === "path" ? input.path : input.source

}

function dir(input: ParseSource) {

return input.type === "path" ? path.dirname(input.path) : input.dir

}

/** Apply {env:VAR} and {file:path} substitutions to config text. */

export async function substitute(input: SubstituteInput) {

const missing = input.missing ?? "error"

let text = input.text.replace(/\{env:([^}]+)\}/g, (_, varName) => {

return process.env[varName] || ""

})

const fileMatches = Array.from(text.matchAll(/\{file:[^}]+\}/g))

if (!fileMatches.length) return text

const configDir = dir(input)

const configSource = source(input)

let out = ""

let cursor = 0

for (const match of fileMatches) {

const token = match[0]

const index = match.index!

out += text.slice(cursor, index)

const lineStart = text.lastIndexOf("\n", index - 1) + 1

const prefix = text.slice(lineStart, index).trimStart()

if (prefix.startsWith("//")) {

out += token

cursor = index + token.length

continue

}

let filePath = token.replace(/^\{file:/, "").replace(/\}$/, "")

if (filePath.startsWith("~/")) {

filePath = path.join(os.homedir(), filePath.slice(2))

}

const resolvedPath = path.isAbsolute(filePath) ? filePath : path.resolve(configDir, filePath)

const fileContent = (

await Filesystem.readText(resolvedPath).catch((error: NodeJS.ErrnoException) => {

if (missing === "empty") return ""

const errMsg = `bad file reference: "${token}"`

if (error.code === "ENOENT") {

throw new InvalidError(

{

path: configSource,

message: errMsg + ` ${resolvedPath} does not exist`,

},

{ cause: error },

)

}

throw new InvalidError({ path: configSource, message: errMsg }, { cause: error })

})

).trim()

out += JSON.stringify(fileContent).slice(1, -1)

cursor = index + token.length

}

out += text.slice(cursor)

return out

}