From 881f57b0473c71917535f9f9ea2736374e02596f Mon Sep 17 00:00:00 2001
From: boombuler <boombuler@gmail.com>
Date: Fri, 2 Sep 2016 19:41:13 +0200
Subject: [PATCH] allow plugins to register autocomplete functions

---
 cmd/micro/autocomplete.go | 23 +++++++++++++++++++++++
 cmd/micro/messenger.go    |  2 ++
 cmd/micro/micro.go        |  1 +
 cmd/micro/plugin.go       | 24 ++++++++++++++++++++++++
 4 files changed, 50 insertions(+)

diff --git a/cmd/micro/autocomplete.go b/cmd/micro/autocomplete.go
index 26c32d0f..3c74501e 100644
--- a/cmd/micro/autocomplete.go
+++ b/cmd/micro/autocomplete.go
@@ -8,6 +8,8 @@ import (
 	"github.com/mitchellh/go-homedir"
 )
 
+var pluginCompletions []func(string) []string
+
 // This file is meant (for now) for autocompletion in command mode, not
 // while coding. This helps micro autocomplete commands and then filenames
 // for example with `vsplit filename`.
@@ -122,3 +124,24 @@ func OptionComplete(input string) (string, []string) {
 	}
 	return chosen, suggestions
 }
+
+// MakeCompletion registeres a function from a plugin for autocomplete commands
+func MakeCompletion(function string) Completion {
+	pluginCompletions = append(pluginCompletions, LuaFunctionComplete(function))
+	return Completion(-len(pluginCompletions))
+}
+
+// PluginComplete autocompletes from plugin function
+func PluginComplete(complete Completion, input string) (chosen string, suggestions []string) {
+	idx := int(-complete) - 1
+
+	if len(pluginCompletions) <= idx {
+		return "", nil
+	}
+	suggestions = pluginCompletions[idx](input)
+
+	if len(suggestions) == 1 {
+		chosen = suggestions[0]
+	}
+	return
+}
diff --git a/cmd/micro/messenger.go b/cmd/micro/messenger.go
index b57d7ff1..c7008063 100644
--- a/cmd/micro/messenger.go
+++ b/cmd/micro/messenger.go
@@ -222,6 +222,8 @@ func (m *Messenger) Prompt(prompt, historyType string, completionTypes ...Comple
 					chosen, suggestions = HelpComplete(currentArg)
 				} else if completionType == OptionCompletion {
 					chosen, suggestions = OptionComplete(currentArg)
+				} else if completionType < NoCompletion {
+					chosen, suggestions = PluginComplete(completionType, currentArg)
 				}
 
 				if len(suggestions) > 1 {
diff --git a/cmd/micro/micro.go b/cmd/micro/micro.go
index 8ee384b9..146336cb 100644
--- a/cmd/micro/micro.go
+++ b/cmd/micro/micro.go
@@ -294,6 +294,7 @@ func main() {
 	L.SetGlobal("HandleCommand", luar.New(L, HandleCommand))
 	L.SetGlobal("HandleShellCommand", luar.New(L, HandleShellCommand))
 	L.SetGlobal("GetLeadingWhitespace", luar.New(L, GetLeadingWhitespace))
+	L.SetGlobal("MakeCompletion", luar.New(L, MakeCompletion))
 
 	// Used for asynchronous jobs
 	L.SetGlobal("JobStart", luar.New(L, JobStart))
diff --git a/cmd/micro/plugin.go b/cmd/micro/plugin.go
index f02f75df..607eb2b6 100644
--- a/cmd/micro/plugin.go
+++ b/cmd/micro/plugin.go
@@ -85,6 +85,30 @@ func LuaFunctionCommand(function string) func([]string) {
 	}
 }
 
+// LuaFunctionComplete returns a function which can be used for autocomplete in plugins
+func LuaFunctionComplete(function string) func(string) []string {
+	return func(input string) (result []string) {
+
+		res, err := Call(function, input)
+		if err != nil {
+			TermMessage(err)
+		}
+		if tbl, ok := res.(*lua.LTable); !ok {
+			TermMessage(function, "should return a table of strings")
+		} else {
+			for i := 1; i <= tbl.Len(); i++ {
+				val := tbl.RawGetInt(i)
+				if v, ok := val.(lua.LString); !ok {
+					TermMessage(function, "should return a table of strings")
+				} else {
+					result = append(result, string(v))
+				}
+			}
+		}
+		return result
+	}
+}
+
 func LuaFunctionJob(function string) func(string, ...string) {
 	return func(output string, args ...string) {
 		_, err := Call(function, unpack(append([]string{output}, args...))...)