1 files changed, 112 insertions, 0 deletions
diff --git a/lua/mason-core/spawn.lua b/lua/mason-core/spawn.lua
new file mode 100644
index 00000000..6b783492
--- /dev/null
+++ b/lua/mason-core/spawn.lua
@@ -0,0 +1,112 @@
+local a = require "mason-core.async"
+local _ = require "mason-core.functional"
+local Result = require "mason-core.result"
+local process = require "mason-core.process"
+local platform = require "mason-core.platform"
+local log = require "mason-core.log"
+
+---@alias JobSpawn table<string, async fun(opts: JobSpawnOpts): Result>
+---@type JobSpawn
+local spawn = {
+    _aliases = {
+        npm = platform.is_win and "npm.cmd" or "npm",
+        gem = platform.is_win and "gem.cmd" or "gem",
+        composer = platform.is_win and "composer.bat" or "composer",
+        gradlew = platform.is_win and "gradlew.bat" or "gradlew",
+        -- for hererocks installations
+        luarocks = (platform.is_win and vim.fn.executable "luarocks.bat" == 1) and "luarocks.bat" or "luarocks",
+        rebar3 = platform.is_win and "rebar3.cmd" or "rebar3",
+    },
+    _flatten_cmd_args = _.compose(_.filter(_.complement(_.equals(vim.NIL))), _.flatten),
+}
+
+local function Failure(err, cmd)
+    return Result.failure(setmetatable(err, {
+        __tostring = function()
+            return ("spawn: %s failed with exit code %s and signal %s. %s"):format(
+                cmd,
+                err.exit_code or "-",
+                err.signal or "-",
+                err.stderr or ""
+            )
+        end,
+    }))
+end
+
+local is_executable = _.memoize(function(cmd)
+    if vim.in_fast_event() then
+        a.scheduler()
+    end
+    return vim.fn.executable(cmd) == 1
+end, _.identity)
+
+---@class SpawnArgs
+---@field with_paths string[] @Optional. Paths to add to the PATH environment variable.
+---@field env table<string, string> @Optional. Example { SOME_ENV = "value", SOME_OTHER_ENV = "some_value" }
+---@field env_raw string[] @Optional. Example: { "SOME_ENV=value", "SOME_OTHER_ENV=some_value" }
+---@field stdio_sink StdioSink @Optional. If provided, will be used to write to stdout and stderr.
+---@field cwd string @Optional
+---@field on_spawn fun(handle: luv_handle, stdio: luv_pipe[]) @Optional. Will be called when the process successfully spawns.
+---@field check_executable boolean @Optional. Whether to check if the provided command is executable (defaults to true).
+
+setmetatable(spawn, {
+    ---@param normalized_cmd string
+    __index = function(self, normalized_cmd)
+        ---@param args SpawnArgs
+        return function(args)
+            local cmd_args = self._flatten_cmd_args(args)
+            local env = args.env
+
+            if args.with_paths then
+                env = env or {}
+                env.PATH = process.extend_path(args.with_paths)
+            end
+
+            ---@type JobSpawnOpts
+            local spawn_args = {
+                stdio_sink = args.stdio_sink,
+                cwd = args.cwd,
+                env = env and process.graft_env(env) or args.env_raw,
+                args = cmd_args,
+            }
+
+            local stdio
+            if not spawn_args.stdio_sink then
+                stdio = process.in_memory_sink()
+                spawn_args.stdio_sink = stdio.sink
+            end
+
+            local cmd = self._aliases[normalized_cmd] or normalized_cmd
+
+            if (env and env.PATH) == nil and args.check_executable ~= false and not is_executable(cmd) then
+                log.fmt_debug("%s is not executable", cmd)
+                return Failure({
+                    stderr = ("%s is not executable"):format(cmd),
+                }, cmd)
+            end
+
+            local _, exit_code, signal = a.wait(function(resolve)
+                local handle, stdio, pid = process.spawn(cmd, spawn_args, resolve)
+                if args.on_spawn and handle and stdio and pid then
+                    args.on_spawn(handle, stdio, pid)
+                end
+            end)
+
+            if exit_code == 0 and signal == 0 then
+                return Result.success {
+                    stdout = stdio and table.concat(stdio.buffers.stdout, "") or nil,
+                    stderr = stdio and table.concat(stdio.buffers.stderr, "") or nil,
+                }
+            else
+                return Failure({
+                    exit_code = exit_code,
+                    signal = signal,
+                    stdout = stdio and table.concat(stdio.buffers.stdout, "") or nil,
+                    stderr = stdio and table.concat(stdio.buffers.stderr, "") or nil,
+                }, cmd)
+            end
+        end
+    end,
+})
+
+return spawn