package main

import (
    "fmt"
    "strings"

    "github.com/mattermost/mattermost/server/public/model"
    "github.com/mattermost/mattermost/server/public/plugin"
)

const helpText = `### Mattermore -- AI Chat Agent

**@mention the bot in any channel to start a conversation.**

**Commands:**

- @mattermore <prompt> -- Chat with the default model
- @mattermore model <name> <prompt> -- Use a specific model
- @mattermore new -- Reset conversation context
- @mattermore model list -- List available models
- @mattermore help -- Show this help
- @mattermore stop -- End the current conversation

You can also use /ai <prompt> as an alternative.

The bot responds only when addressed and disengages naturally.
`

// ExecuteCommand handles the /ai slash command.
func (p *Plugin) ExecuteCommand(_ *plugin.Context, args *model.CommandArgs) (*model.CommandResponse, *model.AppError) {
    trigger := strings.TrimSpace(strings.TrimPrefix(strings.TrimSpace(args.Command), "/ai"))
    parts := parseArgs(trigger)

    switch {
    case len(parts) == 0 || parts[0] == "help":
        return p.response(helpText), nil

    case parts[0] == "new":
        if err := p.conversationStore.Reset(args.UserId, args.ChannelId); err != nil {
            return p.response("Failed to reset conversation."), nil
        }
        return p.response("Conversation reset. Start fresh with @mattermore <prompt>"), nil

    case parts[0] == "model" && len(parts) >= 2 && parts[1] == "list":
        return p.handleModelList(args)

    case parts[0] == "model" && len(parts) >= 3:
        modelName := parts[1]
        prompt := strings.Join(parts[2:], " ")
        return p.handlePrompt(args, modelName, prompt)

    default:
        return p.handlePrompt(args, "", strings.Join(parts, " "))
    }
}

// handlePrompt processes a user prompt and returns the AI response.
func (p *Plugin) handlePrompt(args *model.CommandArgs, modelName, prompt string) (*model.CommandResponse, *model.AppError) {
    cfg := p.getConfiguration()

    // Check rate limit.
    if !p.rateLimiter.Allow(args.UserId) {
        return p.response("Rate limit exceeded. Please wait before sending another request."), nil
    }

    // Check authorization.
    if users := cfg.allowedUsers(); users != nil && !users[args.UserId] {
        return p.response("You are not authorized to use this bot."), nil
    }

    // Check stop words before sending to Ollama.
    if stopWordMatch(prompt, cfg.stopWordSet()) {
        return p.response("Goodbye! Feel free to @mention me again anytime."), nil
    }

    // Build the conversation context.
    var messages []ChatMessage
    messages, err := p.conversationStore.BuildMessages(args.UserId, args.ChannelId, prompt)
    if err != nil {
        return p.response("Failed to build conversation context."), nil
    }

    // Determine model to use.
    activeModel := cfg.DefaultModel
    if modelName != "" {
        activeModel = modelName
    }

    // Send to Ollama.
    resp, err := p.ollamaClient.ChatCompletion(&ChatRequest{
        Model:    activeModel,
        Messages: messages,
        Options:  map[string]any{},
    })
    if err != nil {
        return p.response(fmt.Sprintf("Failed to get response from Ollama: %v", err)), nil
    }

    return &model.CommandResponse{
        ResponseType: model.CommandResponseTypeEphemeral,
        Text:         resp.Message.Content,
    }, nil
}

// handleModelList queries Ollama for available models and returns them.
func (p *Plugin) handleModelList(args *model.CommandArgs) (*model.CommandResponse, *model.AppError) {
    models, err := p.ollamaClient.ListModels()
    if err != nil {
        return p.response("Failed to fetch models from Ollama."), nil
    }
    var b strings.Builder
    b.WriteString("### Available Models\n\n")
    for _, m := range models {
        b.WriteString(fmt.Sprintf("- %s\n", m))
    }
    return p.response(b.String()), nil
}

// parseArgs splits a command string into tokens.
func parseArgs(input string) []string {
    return strings.Fields(input)
}

// response creates a standard ephemeral command response.
func (p *Plugin) response(text string) *model.CommandResponse {
    return &model.CommandResponse{
        ResponseType: model.CommandResponseTypeEphemeral,
        Text:         text,
    }
}