package chat

import (
	"time"

	"git.mlow.ca/mlow/lmcli/pkg/api"
	"git.mlow.ca/mlow/lmcli/pkg/tui/shared"
	"github.com/charmbracelet/bubbles/cursor"
	"github.com/charmbracelet/bubbles/spinner"
	"github.com/charmbracelet/bubbles/textarea"
	"github.com/charmbracelet/bubbles/viewport"
	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/lipgloss"
)

// custom tea.Msg types
type (
	// sent when a conversation is (re)loaded
	msgConversationLoaded struct {
		conversation *api.Conversation
		rootMessages []api.Message
	}
	// sent when a new conversation title generated
	msgConversationTitleGenerated string
	// sent when the conversation has been persisted, triggers a reload of contents
	msgConversationPersisted struct {
		isNew        bool
		conversation *api.Conversation
		messages     []api.Message
	}
	// sent when a conversation's messages are laoded
	msgMessagesLoaded []api.Message
	// a special case of common.MsgError that stops the response waiting animation
	msgChatResponseError error
	// sent on each chunk received from LLM
	msgChatResponseChunk api.Chunk
	// sent on each completed reply
	msgChatResponse *api.Message
	// sent when the response is canceled
	msgChatResponseCanceled struct{}
	// sent when results from a tool call are returned
	msgToolResults []api.ToolResult
	// sent when the given message is made the new selected reply of its parent
	msgSelectedReplyCycled *api.Message
	// sent when the given message is made the new selected root of the current conversation
	msgSelectedRootCycled *api.Message
	// sent when a message's contents are updated and saved
	msgMessageUpdated *api.Message
	// sent when a message is cloned, with the cloned message
	msgMessageCloned *api.Message
)

type focusState int

const (
	focusInput focusState = iota
	focusMessages
)

type editorTarget int

const (
	input editorTarget = iota
	selectedMessage
)

type state int

const (
	idle state = iota
	loading
	pendingResponse
)

type Model struct {
	shared.Shared
	shared.Sections

	// app state
	state           state // current overall status of the view
	conversation    *api.Conversation
	rootMessages    []api.Message
	messages        []api.Message
	selectedMessage int
	editorTarget    editorTarget
	stopSignal      chan struct{}
	replyChan       chan api.Message
	chatReplyChunks chan api.Chunk
	persistence     bool // whether we will save new messages in the conversation

	// ui state
	focus           focusState
	wrap            bool     // whether message content is wrapped to viewport width
	showToolResults bool     // whether tool calls and results are shown
	messageCache    []string // cache of syntax highlighted and wrapped message content
	messageOffsets  []int

	// ui elements
	content     viewport.Model
	input       textarea.Model
	spinner     spinner.Model
	replyCursor cursor.Model // cursor to indicate incoming response

	// metrics
	tokenCount uint
	startTime  time.Time
	elapsed    time.Duration
}

func Chat(shared shared.Shared) Model {
	m := Model{
		Shared: shared,

		state:        idle,
		conversation: &api.Conversation{},
		persistence:  true,

		stopSignal:      make(chan struct{}),
		replyChan:       make(chan api.Message),
		chatReplyChunks: make(chan api.Chunk),

		wrap:            true,
		selectedMessage: -1,

		content: viewport.New(0, 0),
		input:   textarea.New(),
		spinner: spinner.New(spinner.WithSpinner(
			spinner.Spinner{
				Frames: []string{
					".  ",
					".. ",
					"...",
					".. ",
					".  ",
					"   ",
				},
				FPS: time.Second / 3,
			},
		)),
		replyCursor: cursor.New(),
	}

	m.replyCursor.SetChar(" ")
	m.replyCursor.Focus()

	system := shared.Ctx.DefaultSystemPrompt()

	agent := shared.Ctx.GetAgent(shared.Ctx.Config.Defaults.Agent)
	if agent != nil && agent.SystemPrompt != "" {
		system = agent.SystemPrompt
	}

	if system != "" {
		m.messages = api.ApplySystemPrompt(m.messages, system, false)
	}

	m.input.Focus()
	m.input.MaxHeight = 0
	m.input.CharLimit = 0
	m.input.ShowLineNumbers = false
	m.input.Placeholder = "Enter a message"

	m.input.FocusedStyle.CursorLine = lipgloss.NewStyle()
	m.input.FocusedStyle.Base = inputFocusedStyle
	m.input.BlurredStyle.Base = inputBlurredStyle

	return m
}

func (m Model) Init() tea.Cmd {
	return tea.Batch(
		m.waitForResponseChunk(),
	)
}