package chat

import (
	"time"

	"git.mlow.ca/mlow/lmcli/pkg/api"
	"git.mlow.ca/mlow/lmcli/pkg/conversation"
	"git.mlow.ca/mlow/lmcli/pkg/provider"
	"git.mlow.ca/mlow/lmcli/pkg/tui/model"
	"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 new conversation title generated
	msgConversationTitleGenerated string
	// sent when the conversation has been persisted, triggers a reload of contents
	msgConversationPersisted conversation.Conversation
	msgMessagesPersisted []conversation.Message
	// sent when a conversation's messages are laoded
	msgConversationMessagesLoaded struct {
		messages     []conversation.Message
	}
	// a special case of common.MsgError that stops the response waiting animation
	msgChatResponseError struct {
		Err error
	}
	// sent on each chunk received from LLM
	msgChatResponseChunk provider.Chunk
	// sent on each completed reply
	msgChatResponse conversation.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 *conversation.Message
	// sent when the given message is made the new selected root of the current conversation
	msgSelectedRootCycled *conversation.Message
	// sent when a message's contents are updated and saved
	msgMessageUpdated *conversation.Message
	// sent when a message is cloned, with the cloned message
	msgMessageCloned *conversation.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 {
	// App state
	App    *model.AppModel
	Height int
	Width  int

	// Chat view state
	state           state // current overall status of the view
	selectedMessage int
	editorTarget    editorTarget
	stopSignal      chan struct{}
	chatReplyChunks chan provider.Chunk
	persistence     bool // whether we will save new messages in the conversation
	promptCaching   bool // whether prompt caching is enabled

	// UI state
	focus          focusState
	showDetails    bool     // whether various details are shown in the UI (e.g. system prompt, tool calls/results, message metadata)
	wrap           bool     // whether message content is wrapped to viewport width
	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 getSpinner() spinner.Model {
	return spinner.New(spinner.WithSpinner(
		spinner.Spinner{
			Frames: []string{
				"∙∙∙",
				"●∙∙",
				"●●∙",
				"●●●",
				"∙●●",
				"∙∙●",
				"∙∙∙",
				"∙∙●",
				"∙●●",
				"●●●",
				"●●∙",
				"●∙∙",
			},
			FPS: 440 * time.Millisecond,
		},
	))
}

func Chat(app *model.AppModel) *Model {
	m := Model{
		App: app,

		state:       idle,
		persistence: true,

		stopSignal:      make(chan struct{}),
		chatReplyChunks: make(chan provider.Chunk, 1),

		wrap:            true,
		selectedMessage: -1,

		content:     viewport.New(0, 0),
		input:       textarea.New(),
		spinner:     getSpinner(),
		replyCursor: cursor.New(),
	}

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

	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(),
	)
}