Add MessageHasBeenPosted hook with @-mention, thread reply, bot account

server/hooks.go

@@ -0,0 +1,177 @@
+package main
+
+import (
+    "fmt"
+    "strings"
+
+    "github.com/mattermost/mattermost/server/public/model"
+    "github.com/mattermost/mattermost/server/public/plugin"
+)
+
+const botUsername = "mattermore"
+const botDisplayName = "Mattermore AI"
+const botDescription = "AI chat agent powered by Ollama."
+
+// OnActivate is invoked when the plugin is activated.
+func (p *Plugin) OnActivate() error {
+    // Register the /ai slash command.
+    if err := p.API.RegisterCommand(&model.Command{
+        Trigger:          "ai",
+        DisplayName:      "Mattermore",
+        Description:      "AI chat agent powered by Ollama.",
+        AutoComplete:     true,
+        AutoCompleteDesc: "Chat with the AI. Usage: /ai <prompt>",
+        AutoCompleteHint: "<prompt>",
+    }); err != nil {
+        return fmt.Errorf("register command: %w", err)
+    }
+
+    // Ensure the bot account exists.
+    bot := &model.Bot{
+        Username:    botUsername,
+        DisplayName: botDisplayName,
+        Description: botDescription,
+    }
+    createdBot, appErr := p.API.CreateBot(bot)
+    if appErr != nil {
+        return fmt.Errorf("create bot: %w", appErr)
+    }
+    p.botUserID = createdBot.UserId
+
+    // Initialise components.
+    cfg := p.getConfiguration()
+    if cfg == nil {
+        // Load configuration first.
+        if err := p.OnConfigurationChange(); err != nil {
+            return fmt.Errorf("initial configuration: %w", err)
+        }
+        cfg = p.getConfiguration()
+    }
+
+    p.ollamaClient = NewOllamaClient(cfg.OllamaURL)
+    p.conversationStore = NewConversationStore(p.API)
+    p.rateLimiter = NewRateLimiter(cfg.RateLimitPerMinute)
+
+    return nil
+}
+
+// OnDeactivate is invoked when the plugin is deactivated.
+func (p *Plugin) OnDeactivate() error {
+    // The bot account persists across restarts — it will be re-used
+    // on next OnActivate. No explicit cleanup needed.
+    return nil
+}
+
+// Implemented returns the list of hooks this plugin handles.
+func (p *Plugin) Implemented() ([]string, error) {
+    return []string{
+        "OnActivate",
+        "OnDeactivate",
+        "OnConfigurationChange",
+        "ExecuteCommand",
+        "MessageHasBeenPosted",
+    }, nil
+}
+
+// MessageHasBeenPosted is the primary entry point for @-mention interaction.
+func (p *Plugin) MessageHasBeenPosted(c *plugin.Context, post *model.Post) {
+    // Never respond to our own posts.
+    if post.UserId == p.botUserID {
+        return
+    }
+
+    // Never respond to other bots.
+    if post.IsFromOAuthBot() {
+        return
+    }
+
+    // Check if this is a thread reply to a post we made.
+    threadOwned := false
+    if post.RootId != "" {
+        rootPost, appErr := p.API.GetPost(post.RootId)
+        if appErr == nil && rootPost.UserId == p.botUserID {
+            threadOwned = true
+        }
+    }
+
+    // Check if the bot is @-mentioned in the message.
+    mentioned := strings.Contains(
+        strings.ToLower(post.Message),
+        "@"+botUsername,
+    )
+
+    // If not mentioned and not a thread reply, ignore.
+    if !mentioned && !threadOwned {
+        return
+    }
+
+    // Build the prompt by stripping the @-mention.
+    prompt := post.Message
+    if mentioned {
+        prompt = strings.TrimSpace(strings.Replace(
+            strings.ToLower(prompt),
+            "@"+botUsername,
+            "",
+            1,
+        ))
+    }
+
+    // Handle stop words before sending to Ollama.
+    cfg := p.getConfiguration()
+    if stopWordMatch(prompt, cfg.stopWordSet()) {
+        p.postReply(post, "Goodbye! Feel free to @mention me again anytime.")
+        return
+    }
+
+    // Authorisation check.
+    if users := cfg.allowedUsers(); users != nil && !users[post.UserId] {
+        p.postReply(post, "You are not authorised to use this bot.")
+        return
+    }
+
+    // Rate limit check.
+    if !p.rateLimiter.Allow(post.UserId) {
+        p.postReply(post, "Rate limit exceeded. Please wait before sending another request.")
+        return
+    }
+
+    // Build conversation context.
+    messages, err := p.conversationStore.BuildMessages(post.UserId, post.ChannelId, prompt)
+    if err != nil {
+        p.postReply(post, "Failed to build conversation context.")
+        return
+    }
+
+    // Send to Ollama.
+    resp, err := p.ollamaClient.ChatCompletion(&ChatRequest{
+        Model:    cfg.DefaultModel,
+        Messages: messages,
+        Options:  map[string]any{},
+    })
+    if err != nil {
+        p.postReply(post, fmt.Sprintf("Failed to get response from Ollama: %v", err))
+        return
+    }
+
+    p.postReply(post, resp.Message.Content)
+}
+
+// postReply creates a reply post in the same thread as the given post.
+func (p *Plugin) postReply(replyTo *model.Post, text string) {
+    replyPost := &model.Post{
+        UserId:    p.botUserID,
+        ChannelId: replyTo.ChannelId,
+        Message:   text,
+        RootId:    replyTo.RootId,
+    }
+
+    // If the original post has no root, use the original post ID as root.
+    if replyPost.RootId == "" {
+        replyPost.RootId = replyTo.Id
+    }
+
+    if _, appErr := p.API.CreatePost(replyPost); appErr != nil {
+        // Log the failure but don't crash.
+        p.API.LogError("Failed to create reply post", "error", appErr.Error())
+    }
+}

server/store.go

@@ -6,6 +6,8 @@ import (
     "strings"
     "sync"
     "time"
+
+    "github.com/mattermost/mattermost/server/public/model"
 )
 
 // ConversationStore manages conversation context in the Mattermost KV store.
@@ -16,9 +18,9 @@ type ConversationStore struct {
 
 // pluginKV is the subset of the plugin API needed for KV operations.
 type pluginKV interface {
-    KVGet(key string) ([]byte, error)
-    KVSet(key string, value []byte) (bool, error)
-    KVDelete(key string) error
+    KVGet(key string) ([]byte, *model.AppError)
+    KVSet(key string, value []byte) *model.AppError
+    KVDelete(key string) *model.AppError
 }
 
 // NewConversationStore creates a new store backed by the plugin API.
@@ -104,7 +106,7 @@ func (s *ConversationStore) saveSession(session *conversationSession) error {
     if err != nil {
         return fmt.Errorf("marshal session: %w", err)
     }
-    _, err = s.api.KVSet(sessionKey(session.UserID, session.ChannelID), data)
+    err = s.api.KVSet(sessionKey(session.UserID, session.ChannelID), data)
     return err
 }