package model

import (
	"context"
	"fmt"

	"git.mlow.ca/mlow/lmcli/pkg/agents"
	"git.mlow.ca/mlow/lmcli/pkg/api"
	cmdutil "git.mlow.ca/mlow/lmcli/pkg/cmd/util"
	"git.mlow.ca/mlow/lmcli/pkg/conversation"
	"git.mlow.ca/mlow/lmcli/pkg/lmcli"
	"git.mlow.ca/mlow/lmcli/pkg/provider"
	"github.com/charmbracelet/lipgloss"
)

type LoadedConversation struct {
	Conv      conversation.Conversation
	LastReply conversation.Message
}

type AppModel struct {
	Ctx           *lmcli.Context
	Conversations []LoadedConversation
	Conversation  *conversation.Conversation
	Messages      []conversation.Message
	Model         string
	ProviderName  string
	Provider      provider.ChatCompletionProvider
	Agent         *lmcli.Agent
}

func NewAppModel(ctx *lmcli.Context, initialConversation *conversation.Conversation) *AppModel {
	app := &AppModel{
		Ctx:          ctx,
		Conversation: initialConversation,
		Model:        *ctx.Config.Defaults.Model,
	}

	if initialConversation == nil {
		app.NewConversation()
	}

	model, provider, _, _ := ctx.GetModelProvider(*ctx.Config.Defaults.Model, "")
	app.Model = model
	app.ProviderName = provider
	app.Agent = ctx.GetAgent(ctx.Config.Defaults.Agent)
	return app
}

var (
	defaultStyle = lipgloss.NewStyle().Faint(true)
	accentStyle  = defaultStyle.Foreground(lipgloss.Color("6"))
)

func (a *AppModel) ActiveModel(style lipgloss.Style) string {
	defaultStyle := style.Inherit(defaultStyle)
	accentStyle := style.Inherit(accentStyle)
	return defaultStyle.Render(a.Model) + accentStyle.Render("@") + defaultStyle.Render(a.ProviderName)
}

type MessageCycleDirection int

const (
	CycleNext MessageCycleDirection = 1
	CyclePrev MessageCycleDirection = -1
)

func (m *AppModel) ClearConversation() {
	m.Conversation = nil
	m.Messages = []conversation.Message{}
}

func (m *AppModel) ApplySystemPrompt() {
	var system string
	agent := m.Ctx.GetAgent(m.Ctx.Config.Defaults.Agent)
	if agent != nil && agent.SystemPrompt != "" {
		system = agent.SystemPrompt
	}
	if system == "" {
		system = m.Ctx.DefaultSystemPrompt()
	}
	if system != "" {
		m.Messages = conversation.ApplySystemPrompt(m.Messages, system, false)
	}
}

func (m *AppModel) NewConversation() {
	m.ClearConversation()
	m.ApplySystemPrompt()
}

func (m *AppModel) LoadConversations() (error, []LoadedConversation) {
	messages, err := m.Ctx.Conversations.LatestConversationMessages()
	if err != nil {
		return fmt.Errorf("Could not load conversations: %v", err), nil
	}

	conversations := make([]LoadedConversation, len(messages))
	for i, msg := range messages {
		conversations[i] = LoadedConversation{
			Conv:      *msg.Conversation,
			LastReply: msg,
		}
	}
	return nil, conversations
}

func (a *AppModel) LoadConversationMessages() ([]conversation.Message, error) {
	messages, err := a.Ctx.Conversations.PathToLeaf(a.Conversation.SelectedRoot)
	if err != nil {
		return nil, fmt.Errorf("Could not load conversation messages: %v %v", a.Conversation.SelectedRoot, err)
	}
	return messages, nil
}

func (a *AppModel) GenerateConversationTitle(messages []conversation.Message) (string, error) {
	return cmdutil.GenerateTitle(a.Ctx, messages)
}

func (a *AppModel) UpdateConversationTitle(conversation *conversation.Conversation) error {
	return a.Ctx.Conversations.UpdateConversation(conversation)
}

func (a *AppModel) CloneMessage(message conversation.Message, selected bool) (*conversation.Message, error) {
	msg, _, err := a.Ctx.Conversations.CloneBranch(message)
	if err != nil {
		return nil, fmt.Errorf("Could not clone message: %v", err)
	}
	if selected {
		if msg.Parent == nil {
			msg.Conversation.SelectedRoot = msg
			err = a.Ctx.Conversations.UpdateConversation(msg.Conversation)
		} else {
			msg.Parent.SelectedReply = msg
			err = a.Ctx.Conversations.UpdateMessage(msg.Parent)
		}
		if err != nil {
			return nil, fmt.Errorf("Could not update selected message: %v", err)
		}
	}
	return msg, nil
}

func (a *AppModel) UpdateMessageContent(message *conversation.Message) error {
	return a.Ctx.Conversations.UpdateMessage(message)
}

func cycleSelectedMessage(selected *conversation.Message, choices []conversation.Message, dir MessageCycleDirection) (*conversation.Message, error) {
	currentIndex := -1
	for i, reply := range choices {
		if reply.ID == selected.ID {
			currentIndex = i
			break
		}
	}

	if currentIndex < 0 {
		return nil, fmt.Errorf("Selected message %d not found in choices, this is a bug", selected.ID)
	}

	var next int
	if dir == CyclePrev {
		next = (currentIndex - 1 + len(choices)) % len(choices)
	} else {
		next = (currentIndex + 1) % len(choices)
	}
	return &choices[next], nil
}

func (a *AppModel) CycleSelectedRoot(conv *conversation.Conversation, dir MessageCycleDirection) (*conversation.Message, error) {
	if len(conv.RootMessages) < 2 {
		return nil, nil
	}

	nextRoot, err := cycleSelectedMessage(conv.SelectedRoot, conv.RootMessages, dir)
	if err != nil {
		return nil, err
	}

	conv.SelectedRoot = nextRoot
	err = a.Ctx.Conversations.UpdateConversation(conv)
	if err != nil {
		return nil, fmt.Errorf("Could not update conversation SelectedRoot: %v", err)
	}
	return nextRoot, nil
}

func (a *AppModel) CycleSelectedReply(message *conversation.Message, dir MessageCycleDirection) (*conversation.Message, error) {
	if len(message.Replies) < 2 {
		return nil, nil
	}

	nextReply, err := cycleSelectedMessage(message.SelectedReply, message.Replies, dir)
	if err != nil {
		return nil, err
	}

	message.SelectedReply = nextReply
	err = a.Ctx.Conversations.UpdateMessage(message)
	if err != nil {
		return nil, fmt.Errorf("Could not update message SelectedReply: %v", err)
	}
	return nextReply, nil
}

func (a *AppModel) PersistConversation(conversation *conversation.Conversation, messages []conversation.Message) (*conversation.Conversation, []conversation.Message, error) {
	var err error
	if conversation == nil || conversation.ID == 0 {
		conversation, messages, err = a.Ctx.Conversations.StartConversation(messages...)
		if err != nil {
			return nil, nil, fmt.Errorf("Could not start new conversation: %v", err)
		}
		return conversation, messages, nil
	}

	for i := range messages {
		if messages[i].ID > 0 {
			err := a.Ctx.Conversations.UpdateMessage(&messages[i])
			if err != nil {
				return nil, nil, err
			}
		} else if i > 0 {
			saved, err := a.Ctx.Conversations.Reply(&messages[i-1], messages[i])
			if err != nil {
				return nil, nil, err
			}
			messages[i] = saved[0]
		} else {
			return nil, nil, fmt.Errorf("Error: no messages to reply to")
		}
	}
	return conversation, messages, nil
}

func (a *AppModel) ExecuteToolCalls(toolCalls []api.ToolCall) ([]api.ToolResult, error) {
	agent := a.Ctx.GetAgent(a.Ctx.Config.Defaults.Agent)
	if agent == nil {
		return nil, fmt.Errorf("Attempted to execute tool calls with no agent configured")
	}

	return agents.ExecuteToolCalls(toolCalls, agent.Toolbox)
}

func (a *AppModel) Prompt(
	messages []conversation.Message,
	chatReplyChunks chan provider.Chunk,
	stopSignal chan struct{},
) (*conversation.Message, error) {
	model, _, p, err := a.Ctx.GetModelProvider(a.Model, a.ProviderName)
	if err != nil {
		return nil, err
	}

	params := provider.RequestParameters{
		Model:       model,
		MaxTokens:   *a.Ctx.Config.Defaults.MaxTokens,
		Temperature: *a.Ctx.Config.Defaults.Temperature,
	}

	if a.Agent != nil {
		params.Toolbox = a.Agent.Toolbox
	}

	ctx, cancel := context.WithCancel(context.Background())

	go func() {
		select {
		case <-stopSignal:
			cancel()
		}
	}()

	msg, err := p.CreateChatCompletionStream(
		ctx, params, conversation.MessagesToAPI(messages), chatReplyChunks,
	)

	if msg != nil {
		msg := conversation.MessageFromAPI(*msg)
		msg.Metadata.GenerationProvider = &a.ProviderName
		msg.Metadata.GenerationModel = &a.Model
		return &msg, err
	}
	return nil, err
}