// gorc project
// Copyright (C) 2022 IllusionMan1212
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program; if not, see https://www.gnu.org/licenses.

package irc

import (
	"crypto/tls"
	"fmt"
	"log"
	"net"
	"strings"
	"time"

	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/lipgloss"
	"github.com/illusionman1212/gorc/irc/commands"
	"github.com/illusionman1212/gorc/ui"
)

type Message struct {
	DateTime   time.Time
	Tags       MessageTags // starts with @ | Optional
	Source     string      // starts with : | Optional
	Command    string      // can either be a string or a numeric value | Required
	Parameters []string    // Optional (Dependant on command)
}

type MessageTags map[string]string

type User struct {
	// User prefix in channel
	Prefix string
}

type Node[T any] struct {
	Next  *Node[T]
	Prev  *Node[T]
	Value T
}

type Channel struct {
	// Channel name
	Name string

	// Channel topic
	Topic string

	// Channel messages history
	History string

	// Date of the last message we received in this channel
	LastUpdatedDate time.Time

	// Users in this channel
	// The map key is the user's nickname
	// and the user struct holds data about that user
	// such as, prefixes in this channel and etc...
	Users map[string]User
}

type Client struct {
	// tcp connection
	TCPConn net.Conn

	// Host that client is connected to
	Host string

	// Port that client is connected to
	Port string

	// Nickname currently in use by the user
	Nickname string

	// The root of the doubly linked list of channel
	RootChannel *Node[Channel]

	// Active channel
	ActiveChannel *Node[Channel]

	// The channel to join immediately after registration completes.
	InitialChannel string

	// Reference to the bubbletea program
	Tea *tea.Program

	// Index of the first visible tab in the tab bar
	// FirstTabIndexInTabBar int

	// Index of the last visible tab in the tab bar
	// LastTabIndexInTabBar int

	// The acknowledged capabilities
	EnabledCapabilities Capabilities

	// The features currently enabled for this client
	EnabledFeatures Features
}

type Capabilities map[string]string
type Features map[string]string

type MsgFmtOpts struct {
	WithTimestamp bool
	// TODO: make these a bitset? they should compliment eachother instead of conflicting or rendering twice.
	AsServerMsg bool
	AsErrorMsg  bool

	NotImpl bool
}

var unimpl = lipgloss.NewStyle().Foreground(ui.ErrorColor).Render("[UNIMPL]")
var serverMsgStyle = lipgloss.NewStyle().Foreground(ui.ServerMsgColor)
var errorMsgStyle = lipgloss.NewStyle().Foreground(ui.ErrorColor)
var timestampStyle = serverMsgStyle
var dateStyle = lipgloss.NewStyle().Foreground(ui.DateColor)

const CRLF = "\r\n"

func (m *Message) SetTimestamp() {
	if serverTime, ok := m.Tags["time"]; ok {
		t, err := time.Parse("2006-01-02T15:04:05.000Z", serverTime)
		if err != nil {
			// TODO: properly handle error
			log.Fatalln(err)
		}
		m.DateTime = t.Local()
	} else {
		m.DateTime = time.Now()
	}
}

func (c *Channel) AppendMsg(datetime time.Time, fullMsg string, opts MsgFmtOpts) {
	prefixes := ""
	style := ui.DefaultStyle

	if opts.WithTimestamp {
		str := fmt.Sprintf("[%02d:%02d]", datetime.Hour(), datetime.Minute())
		prefixes += timestampStyle.Render(str) + " "
	}

	if opts.NotImpl {
		prefixes += unimpl + " "
	}

	if opts.AsServerMsg {
		prefixes += serverMsgStyle.Render("==") + " "
		style = serverMsgStyle
	}

	if opts.AsErrorMsg {
		prefixes += errorMsgStyle.Render("==") + " "
		style = errorMsgStyle
	}

	if datetime.Year() > c.LastUpdatedDate.Year() || datetime.YearDay() > c.LastUpdatedDate.YearDay() {
		c.LastUpdatedDate = datetime
		dateMsg := fmt.Sprintf("————— %s %d —————", c.LastUpdatedDate.Month().String(), c.LastUpdatedDate.Day())
		c.History += dateStyle.Render(dateMsg) + CRLF
	}

	c.History += prefixes + style.Render(fullMsg) + CRLF
}

func (c *Client) Initialize(host string, port string, tlsEnabled bool) {
	addr := fmt.Sprintf("%s:%s", host, port)

	c.Host = host
	c.Port = port
	c.EnabledCapabilities = make(Capabilities, 0)
	c.EnabledFeatures = make(Features, 0)

	if tlsEnabled {
		cfg := &tls.Config{ServerName: host}
		conn, err := tls.Dial("tcp", addr, cfg)
		if err != nil {
			// TODO: properly handle the error instead of Fatal-ing (failed to initiate a connection to server)
			log.Fatal(err)
		}

		c.TCPConn = conn
		return
	}

	addrTCP, err := net.ResolveTCPAddr("tcp", addr)
	if err != nil {
		log.Fatal(err)
	}

	conn, err := net.DialTCP("tcp", nil, addrTCP)
	if err != nil {
		log.Fatal(err)
	}

	c.TCPConn = conn
}

func (c *Client) Register(nick string, password string, channel string) {
	hostChannel := Channel{
		Name:  c.Host,
		Users: make(map[string]User),
	}
	root := &Node[Channel]{Value: hostChannel}
	root.Next = root
	root.Prev = root

	c.ActiveChannel = root
	c.RootChannel = root

	c.SendCommand(commands.CAP, "LS", "302")
	if password != "" {
		c.SendCommand(commands.PASS, password)
	}
	c.SendCommand(commands.NICK, nick)
	// set user-wanted nickname
	c.Nickname = nick
	c.SendCommand(commands.USER, nick, "0", "*", nick)
}

func (c *Client) AppendChannel(channel Channel) *Node[Channel] {
	first := c.RootChannel
	last := c.RootChannel.Prev

	newNode := &Node[Channel]{
		Value: channel,
		Next:  first,
		Prev:  last,
	}

	last.Next = newNode
	first.Prev = newNode

	return newNode
}

func (c *Client) RemoveChannel(channel *Node[Channel]) {
	prev := channel.Prev
	next := channel.Next

	prev.Next = next
	next.Prev = prev

	channel.Prev = nil
	channel.Next = nil
}

func (c *Client) SendCommand(cmd string, params ...string) {
	if c.TCPConn == nil {
		// TODO: properly handle the error instead of Fatal-ing
		log.Fatal("Attempted to write data to nil connection")
	}

	paramsString := ""

	// if we have more than 1 param
	if len(params) > 1 {
		lastParam := params[len(params)-1]
		// if the last param is a trailing param
		// we prepend a colon to it
		if strings.Contains(lastParam, " ") {
			lastParam = " :" + lastParam
		} else {
			lastParam = " " + lastParam
		}

		paramsString = " " + strings.Join(params[:len(params)-1], " ")
		paramsString += lastParam

		// if we have exactly 1 param and it's not empty
	} else if len(params) == 1 && params[0] != "" {
		// if this 1 param contains spaces, we prepend a colon
		if strings.Contains(params[0], " ") {
			paramsString = " :" + params[0]
		} else {
			paramsString = " " + params[0]
		}
	}

	c.TCPConn.Write([]byte(cmd + paramsString + CRLF))
}