scripts/.lune/lib/exec.luau

--> lib: Builder pattern class to spawn child processes

local process = require("@lune/process")
local stdio = require("@lune/stdio")

local CommandBuilder = {}

export type CommandBuilder = typeof(setmetatable({} :: CommandBuilderFields, { __index = CommandBuilder }))
type CommandBuilderFields = {
    program: string,
    args: { string },
    stdioStrategy: IoStrategyMapping?,
}
export type StdioStrategy = "pipe" | "forward" | "none"
export type IoStrategyMapping = {
    stdout: StdioStrategy?,
    stderr: StdioStrategy?,
}

local DEFAULT_STDIO_STRATEGY: IoStrategyMapping = {
    stdout = "pipe",
    stderr = "pipe",
}
function CommandBuilder.new(program: string)
    return setmetatable(
        {
            program = program,
            args = {},
            stdioStrategy = nil,
        } :: CommandBuilderFields,
        {
            __index = CommandBuilder,
        }
    )
end

function CommandBuilder.withArg(self: CommandBuilder, arg: string): CommandBuilder
    table.insert(self.args, arg)
    return self
end

function CommandBuilder.withArgs(self: CommandBuilder, args: { string }): CommandBuilder
    for _, arg in args do
        self:withArg(arg)
    end

    return self
end

function CommandBuilder.withStdioStrategy(
    self: CommandBuilder,
    strategy: StdioStrategy | IoStrategyMapping
): CommandBuilder
    self.stdioStrategy = if typeof(strategy) == "string"
        then {
            stdout = strategy,
            stderr = strategy,
        }
        else strategy
    return self
end

local function intoSpawnOptionsStdioKind(strategy: StdioStrategy): process.SpawnOptionsStdioKind
    if strategy == "pipe" then
        return "default"
    end

    if strategy == "forward" then
        return "forward"
    end

    if strategy == "none" then
        return "none"
    end

    error(`Non-strategy provided: {strategy}`)
end

function CommandBuilder.exec(self: CommandBuilder): process.SpawnResult
    print("$", stdio.style("dim") .. self.program, table.concat(self.args, " ") .. stdio.style("reset"))

    local function translateIoStrategyMappings(mappings: IoStrategyMapping)
        local translatedMappings: process.SpawnOptionsStdio = {}
        for field, value in mappings do
            translatedMappings[field] = intoSpawnOptionsStdioKind(value)
        end

        return translatedMappings
    end

    local child = process.spawn(self.program, self.args, {
        shell = true,
        stdio = translateIoStrategyMappings(self.stdioStrategy or DEFAULT_STDIO_STRATEGY),
    })

    if not child.ok then
        print(`\n{stdio.color("red")}[luau-lsp]{stdio.color("reset")} Exited with code`, child.code)
    end

    return child
end

return CommandBuilder