Improves the installation process

Now errors and outputs is logged in the Nim output windows as they happen.
This PR also prepares the local installation environment. Unfortunately it errors, so Nimble needs to be improved.
cc nim-lang#9

src/nimLsp.nim

@@ -2,7 +2,7 @@ import std/[jsconsole, strutils, jsfetch, asyncjs, sugar, sequtils, options, str
 import platform/[vscodeApi, languageClientApi]
 
 import platform/js/[jsNodeFs, jsNodePath, jsNodeCp, jsNodeUtil]
-
+import nimutils
 from std/strformat import fmt
 from tools/nimBinTools import getNimbleExecPath, getBinPath
 from spec import ExtensionState
@@ -116,16 +116,28 @@ proc handleLspVersion(nimlangserver: cstring, latestVersion: LSPVersion) =
   global.setTimeout(onLspTimeout, 1000)
   process = cp.exec((nimlangserver & " --version"), ExecOptions(), onExec)    
 
-proc getLspPath(): cstring = 
-  var lspPath = vscode.workspace.getConfiguration("nim").getStr("lsp.path")
-  if lspPath.isNil or lspPath == "":
-    lspPath = getBinPath("nimlangserver")
-  console.log("Attempting to use nimlangserver at " & lspPath)
-  lspPath
+proc isValidLspPath(lspPath: cstring): bool = 
+  result = not lspPath.isNil and lspPath != "" and fs.existsSync(path.resolve(lspPath))  
+  if lspPath.isNil: 
+    console.log("lspPath is nil")
+  else:
+    console.log(fmt"isValidLspPath({lspPath}) = {result}".cstring)
+
+proc getLspPath(state: ExtensionState): cstring = 
+  #[
+    We first try to use the path from the nim.lsp.path setting.
+    If path is not set, we try to use the global nimlangserver binary.
+    If the global binary is not found, (TODO) we try to use the local nimlangserver binary.
+  ]#
+  result = vscode.workspace.getConfiguration("nim").getStr("lsp.path")
+  if not isValidLspPath(result):
+    result = getBinPath("nimlangserver")
+    if not isValidLspPath(result):
+      result = path.join(state.ctx.storagePath, "bin", "nimlangserver")
 
 proc startLanguageServer(tryInstall: bool, state: ExtensionState) {.async.} =
-  let rawPath = getLspPath()
-  if rawPath.isNil or not fs.existsSync(path.resolve(rawPath)):
+  let rawPath = getLspPath(state)
+  if not isValidLspPath(rawPath):
     console.log("nimlangserver not found on path")
     if tryInstall and not state.installPerformed:
       let command = getNimbleExecPath() & " install nimlangserver --accept"
@@ -144,12 +156,30 @@ proc startLanguageServer(tryInstall: bool, state: ExtensionState) {.async.} =
               state.installPerformed = true
               vscode.window.showInformationMessage(
                 cstring(fmt "Trying to install nimlangserver via '{command}'"))
-              discard cp.exec(
-                command,
-                ExecOptions{},
-                proc(err: ExecError, stdout: cstring, stderr: cstring): void {.async.} =
+              let args: seq[cstring] = @["install nimlangserver", "--accept"]
+              var process = cp.spawn(
+                  getNimbleExecPath(), args, 
+                  SpawnOptions(shell: true))
+              process.stdout.onceData(proc(data: Buffer) =
+                outputLine(data.toString())
+              )
+              process.stderr.onceData(proc(data: Buffer) =
+                #TODO properly print error message
+                #Notice this also prints warnings
+                let msg =  $data.toString()
+                if msg.contains("Warning: "):
+                  outputLine(("[Warning]" & msg).cstring)
+                else:
+                  outputLine(("[Error]" & msg).cstring)
+              )
+              process.onClose(proc(code: cint, signal: cstring): void =
+                if code == 0:
+                  outputLine("Nimble install successfully")
+                  discard startLanguageServer(false, state)
                   console.log("Nimble install finished, validating by checking if nimlangserver is present.")
-                  await startLanguageServer(false, state))
+                else:
+                  outputLine("Nimble install failed.")
+              )
           value
         ,
         onrejected = proc(reason: JsRoot): JsRoot =

src/platform/js/jsNodeCp.nim

@@ -43,6 +43,7 @@ type
 
   SpawnOptions* = ref object
     cwd*: cstring
+    shell*: bool
 
   SpawnSyncOptions* = ref object
     cwd*: cstring