package util

import (
	"context"
	"fmt"
	"os"
	"strings"
	"time"

	"git.mlow.ca/mlow/lmcli/pkg/lmcli"
	"git.mlow.ca/mlow/lmcli/pkg/lmcli/model"
	"git.mlow.ca/mlow/lmcli/pkg/util"
	"github.com/charmbracelet/lipgloss"
)

// Prompt prompts the configured the configured model and streams the response
// to stdout. Returns all model reply messages.
func Prompt(ctx *lmcli.Context, messages []model.Message, callback func(model.Message)) (string, error) {
	content := make(chan string) // receives the reponse from LLM
	defer close(content)

	// render all content received over the channel
	go ShowDelayedContent(content)

	completionProvider, err := ctx.GetCompletionProvider(*ctx.Config.Defaults.Model)
	if err != nil {
		return "", err
	}

	requestParams := model.RequestParameters{
		Model:       *ctx.Config.Defaults.Model,
		MaxTokens:   *ctx.Config.Defaults.MaxTokens,
		Temperature: *ctx.Config.Defaults.Temperature,
		ToolBag:     ctx.EnabledTools,
	}

	response, err := completionProvider.CreateChatCompletionStream(
		context.Background(), requestParams, messages, callback, content,
	)
	if response != "" {
		// there was some content, so break to a new line after it
		fmt.Println()

		if err != nil {
			lmcli.Warn("Received partial response. Error: %v\n", err)
			err = nil
		}
	}
	return response, err
}

// lookupConversation either returns the conversation found by the
// short name or exits the program
func LookupConversation(ctx *lmcli.Context, shortName string) *model.Conversation {
	c, err := ctx.Store.ConversationByShortName(shortName)
	if err != nil {
		lmcli.Fatal("Could not lookup conversation: %v\n", err)
	}
	if c.ID == 0 {
		lmcli.Fatal("Conversation not found: %s\n", shortName)
	}
	return c
}

func LookupConversationE(ctx *lmcli.Context, shortName string) (*model.Conversation, error) {
	c, err := ctx.Store.ConversationByShortName(shortName)
	if err != nil {
		return nil, fmt.Errorf("Could not lookup conversation: %v", err)
	}
	if c.ID == 0 {
		return nil, fmt.Errorf("Conversation not found: %s", shortName)
	}
	return c, nil
}

// handleConversationReply handles sending messages to an existing
// conversation, optionally persisting both the sent replies and responses.
func HandleConversationReply(ctx *lmcli.Context, c *model.Conversation, persist bool, toSend ...model.Message) {
	existing, err := ctx.Store.Messages(c)
	if err != nil {
		lmcli.Fatal("Could not retrieve messages for conversation: %s\n", c.Title)
	}

	if persist {
		for _, message := range toSend {
			err = ctx.Store.SaveMessage(&message)
			if err != nil {
				lmcli.Warn("Could not save %s message: %v\n", message.Role, err)
			}
		}
	}

	allMessages := append(existing, toSend...)

	RenderConversation(ctx, allMessages, true)

	// render a message header with no contents
	RenderMessage(ctx, (&model.Message{Role: model.MessageRoleAssistant}))

	replyCallback := func(reply model.Message) {
		if !persist {
			return
		}

		reply.ConversationID = c.ID
		err = ctx.Store.SaveMessage(&reply)
		if err != nil {
			lmcli.Warn("Could not save reply: %v\n", err)
		}
	}

	_, err = Prompt(ctx, allMessages, replyCallback)
	if err != nil {
		lmcli.Fatal("Error fetching LLM response: %v\n", err)
	}
}

func FormatForExternalPrompt(messages []model.Message, system bool) string {
	sb := strings.Builder{}
	for _, message := range messages {
		if message.Content == "" {
			continue
		}
		switch message.Role {
		case model.MessageRoleAssistant, model.MessageRoleToolCall:
			sb.WriteString("Assistant:\n\n")
		case model.MessageRoleUser:
			sb.WriteString("User:\n\n")
		default:
			continue
		}
		sb.WriteString(fmt.Sprintf("%s", lipgloss.NewStyle().PaddingLeft(1).Render(message.Content)))
	}
	return sb.String()
}

func GenerateTitle(ctx *lmcli.Context, c *model.Conversation) (string, error) {
	messages, err := ctx.Store.Messages(c)
	if err != nil {
		return "", err
	}

	const prompt = `Above is an excerpt from a conversation between a user and AI assistant. Please reply with a short title (no more than 8 words) that reflects the topic of the conversation, read from the user's perspective.

Example conversation:

"""
User:

  Hello!

Assistant:

  Hello! How may I assist you?
"""

Example response:

"""
Title: A brief introduction
"""
`
	conversation := FormatForExternalPrompt(messages, false)

	generateRequest := []model.Message{
		{
			Role:    model.MessageRoleUser,
			Content: fmt.Sprintf("\"\"\"\n%s\n\"\"\"\n\n%s", conversation, prompt),
		},
	}

	completionProvider, err := ctx.GetCompletionProvider(*ctx.Config.Conversations.TitleGenerationModel)
	if err != nil {
		return "", err
	}

	requestParams := model.RequestParameters{
		Model:     *ctx.Config.Conversations.TitleGenerationModel,
		MaxTokens: 25,
	}

	response, err := completionProvider.CreateChatCompletion(context.Background(), requestParams, generateRequest, nil)
	if err != nil {
		return "", err
	}

	response = strings.TrimPrefix(response, "Title: ")
	response = strings.Trim(response, "\"")
	response = strings.TrimSpace(response)

	return response, nil
}

// ShowWaitAnimation prints an animated ellipses to stdout until something is
// received on the signal channel. An empty string sent to the channel to
// notify the caller that the animation has completed (carriage returned).
func ShowWaitAnimation(signal chan any) {
	// Save the current cursor position
	fmt.Print("\033[s")

	animationStep := 0
	for {
		select {
		case _ = <-signal:
			// Relmcli the cursor position
			fmt.Print("\033[u")
			signal <- ""
			return
		default:
			// Move the cursor to the saved position
			modSix := animationStep % 6
			if modSix == 3 || modSix == 0 {
				fmt.Print("\033[u")
			}
			if modSix < 3 {
				fmt.Print(".")
			} else {
				fmt.Print(" ")
			}
			animationStep++
			time.Sleep(250 * time.Millisecond)
		}
	}
}

// ShowDelayedContent displays a waiting animation to stdout while waiting
// for content to be received on the provided channel. As soon as any (possibly
// chunked) content is received on the channel, the waiting animation is
// replaced by the content.
// Blocks until the channel is closed.
func ShowDelayedContent(content <-chan string) {
	waitSignal := make(chan any)
	go ShowWaitAnimation(waitSignal)

	firstChunk := true
	for chunk := range content {
		if firstChunk {
			// notify wait animation that we've received data
			waitSignal <- ""
			// wait for signal that wait animation has completed
			<-waitSignal
			firstChunk = false
		}
		fmt.Print(chunk)
	}
}

// RenderConversation renders the given messages to TTY, with optional space
// for a subsequent message. spaceForResponse controls how many '\n' characters
// are printed immediately after the final message (1 if false, 2 if true)
func RenderConversation(ctx *lmcli.Context, messages []model.Message, spaceForResponse bool) {
	l := len(messages)
	for i, message := range messages {
		RenderMessage(ctx, &message)
		if i < l-1 || spaceForResponse {
			// print an additional space before the next message
			fmt.Println()
		}
	}
}

func RenderMessage(ctx *lmcli.Context, m *model.Message) {
	var messageAge string
	if m.CreatedAt.IsZero() {
		messageAge = "now"
	} else {
		now := time.Now()
		messageAge = util.HumanTimeElapsedSince(now.Sub(m.CreatedAt))
	}

	headerStyle := lipgloss.NewStyle().Bold(true)

	switch m.Role {
	case model.MessageRoleSystem:
		headerStyle = headerStyle.Foreground(lipgloss.Color("9")) // bright red
	case model.MessageRoleUser:
		headerStyle = headerStyle.Foreground(lipgloss.Color("10")) // bright green
	case model.MessageRoleAssistant:
		headerStyle = headerStyle.Foreground(lipgloss.Color("12")) // bright blue
	}

	role := headerStyle.Render(m.Role.FriendlyRole())

	separatorStyle := lipgloss.NewStyle().Foreground(lipgloss.Color("3"))
	separator := separatorStyle.Render("===")
	timestamp := separatorStyle.Render(messageAge)

	fmt.Printf("%s %s - %s %s\n\n", separator, role, timestamp, separator)
	if m.Content != "" {
		ctx.Chroma.Highlight(os.Stdout, m.Content)
		fmt.Println()
	}
}