package soju

import (
	"bufio"
	"context"
	"crypto/tls"
	"fmt"
	"log/slog"
	"net"
	"strconv"
	"strings"
	"sync/atomic"
	"time"

	"sojuboy/internal/store"

	irc "github.com/sorcix/irc"
)

type RawClient struct {
	Server   string
	Port     int
	UseTLS   bool
	Nick     string
	Username string // full identity: username/network@client
	Realname string
	Password string // PASS <password>
	Channels []string

	// Number of messages to fetch via CHATHISTORY LATEST per channel after join.
	BackfillLatest int

	OnPrivmsg func(channel, author, text, msgid string, at time.Time)

	Logger *slog.Logger
	Debug  bool

	// Store is used to compute last-seen timestamp for CHATHISTORY.
	Store *store.Store

	// Readiness/metrics hooks
	ConnectedGauge *int64 // 0/1
	IsReady        *int32 // 0/1 atomic flag
}

func (c *RawClient) setConnected(v bool) {
	if c.ConnectedGauge != nil {
		if v {
			atomic.StoreInt64(c.ConnectedGauge, 1)
		} else {
			atomic.StoreInt64(c.ConnectedGauge, 0)
		}
	}
	if c.IsReady != nil {
		if v {
			atomic.StoreInt32(c.IsReady, 1)
		} else {
			atomic.StoreInt32(c.IsReady, 0)
		}
	}
}

func (c *RawClient) Run(ctx context.Context) error {
	backoff := time.Second
	for {
		if err := c.runOnce(ctx); err != nil {
			if ctx.Err() != nil {
				return ctx.Err()
			}
			if c.Logger != nil {
				c.Logger.Error("raw soju client stopped", "err", err)
			}
			time.Sleep(backoff)
			if backoff < 30*time.Second {
				backoff *= 2
			}
			continue
		}
		return nil
	}
}

func (c *RawClient) runOnce(ctx context.Context) error {
	address := net.JoinHostPort(c.Server, strconv.Itoa(c.Port))
	var conn net.Conn
	var err error
	if c.UseTLS {
		tlsCfg := &tls.Config{ServerName: c.Server, MinVersion: tls.VersionTLS12}
		conn, err = tls.Dial("tcp", address, tlsCfg)
	} else {
		conn, err = net.Dial("tcp", address)
	}
	if err != nil {
		return err
	}
	defer conn.Close()

	rw := bufio.NewReadWriter(bufio.NewReader(conn), bufio.NewWriter(conn))

	write := func(line string) error {
		out := line
		if strings.HasPrefix(strings.ToUpper(line), "PASS ") {
			out = "PASS ********"
		}
		if c.Debug && c.Logger != nil {
			c.Logger.Debug("irc>", "line", out)
		}
		if _, err := rw.WriteString(line + "\r\n"); err != nil {
			return err
		}
		return rw.Flush()
	}

	// Request capabilities needed for chathistory and accurate timestamps.
	_ = write("CAP LS 302")
	_ = write("CAP REQ :server-time batch message-tags draft/chathistory draft/event-playback echo-message cap-notify")
	_ = write("CAP END")

	// Authenticate with PASS/NICK/USER
	if c.Password != "" {
		if err := write("PASS " + c.Password); err != nil {
			return err
		}
	}
	if err := write("NICK " + c.Nick); err != nil {
		return err
	}
	user := c.Username
	if user == "" {
		user = c.Nick
	}
	host := c.Server
	if err := write(fmt.Sprintf("USER %s %s %s :%s", user, user, host, c.Realname)); err != nil {
		return err
	}

	// Reader loop
	connected := false
	eventPlayback := false
	selfJoined := map[string]bool{}

	for {
		select {
		case <-ctx.Done():
			return ctx.Err()
		default:
		}
		rawLine, err := rw.ReadString('\n')
		if err != nil {
			return err
		}
		rawLine = strings.TrimRight(rawLine, "\r\n")
		if rawLine == "" {
			continue
		}
		if c.Debug && c.Logger != nil {
			c.Logger.Debug("irc<", "line", rawLine)
		}

		// Parse IRCv3 tags if present
		var tags map[string]string
		line := rawLine
		if strings.HasPrefix(line, "@") {
			sp := strings.IndexByte(line, ' ')
			if sp > 0 {
				tags = parseTags(line[1:sp])
				line = strings.TrimSpace(line[sp+1:])
			}
		}

		msg := irc.ParseMessage(line)
		if msg == nil {
			continue
		}
		cmd := strings.ToUpper(msg.Command)
		switch cmd {
		case "CAP":
			// Examples: :bnc CAP * ACK :server-time batch message-tags draft/chathistory draft/event-playback
			if len(msg.Params) >= 3 {
				sub := strings.ToUpper(msg.Params[1])
				caps := strings.TrimPrefix(msg.Params[2], ":")
				switch sub {
				case "ACK":
					if strings.Contains(caps, "draft/event-playback") {
						eventPlayback = true
						if c.Logger != nil {
							c.Logger.Info("cap enabled", "cap", "draft/event-playback")
						}
					}
				case "NEW":
					if strings.Contains(caps, "draft/event-playback") && !eventPlayback {
						_ = write("CAP REQ :draft/event-playback")
					}
				}
			}
		case "PING":
			if len(msg.Params) > 0 {
				_ = write("PONG :" + msg.Params[len(msg.Params)-1])
			}
		case "001": // welcome
			connected = true
			c.setConnected(true)
			if c.Logger != nil {
				c.Logger.Info("connected", "server", c.Server, "auth", "raw")
			}
			for _, ch := range c.Channels {
				_ = write("JOIN " + ch)
				if c.Logger != nil {
					c.Logger.Info("join requested", "channel", ch)
				}
			}
		case "JOIN":
			if len(msg.Params) == 0 {
				break
			}
			ch := msg.Params[0]
			nick := nickFromPrefix(msg.Prefix)
			if c.Logger != nil {
				c.Logger.Info("joined", "channel", ch, "nick", nick)
			}
			if nick == c.Nick && !selfJoined[ch] {
				selfJoined[ch] = true
				if !eventPlayback && c.BackfillLatest > 0 {
					// Use last seen timestamp if available
					since := time.Now().Add(-24 * time.Hour) // default fallback
					if c.Store != nil {
						if t, ok, err := c.Store.LastMessageTime(ctx, ch); err == nil && ok {
							since = t
						}
					}
					// ISO-8601 / RFC3339 format
					ts := since.UTC().Format(time.RFC3339Nano)
					_ = write(fmt.Sprintf("CHATHISTORY LATEST %s timestamp=%s %d", ch, ts, c.BackfillLatest))
				}
			}
		case "PRIVMSG":
			if len(msg.Params) < 1 {
				continue
			}
			target := msg.Params[0]
			var text string
			if len(msg.Params) >= 2 {
				text = msg.Params[1]
			} else if msg.Trailing != "" {
				text = msg.Trailing
			} else {
				continue
			}
			at := time.Now()
			if ts, ok := tags["time"]; ok && ts != "" {
				if t, e := time.Parse(time.RFC3339Nano, ts); e == nil {
					at = t
				} else if t2, e2 := time.Parse(time.RFC3339, ts); e2 == nil {
					at = t2
				}
			}
			msgid := tags["soju-msgid"]
			if msgid == "" {
				msgid = tags["msgid"]
			}
			if c.OnPrivmsg != nil {
				c.OnPrivmsg(target, nickFromPrefix(msg.Prefix), text, msgid, at)
			}
		case "ERROR":
			c.setConnected(false)
			return fmt.Errorf("server closed: %s", strings.Join(msg.Params, " "))
		}

		_ = connected
	}
}

func nickFromPrefix(pfx *irc.Prefix) string {
	if pfx == nil {
		return ""
	}
	if pfx.Name != "" {
		return pfx.Name
	}
	if pfx.User != "" {
		return pfx.User
	}
	if pfx.Host != "" {
		return pfx.Host
	}
	return ""
}

func parseTags(s string) map[string]string {
	out := make(map[string]string)
	if s == "" {
		return out
	}
	parts := strings.Split(s, ";")
	for _, p := range parts {
		if p == "" {
			continue
		}
		kv := strings.SplitN(p, "=", 2)
		key := kv[0]
		val := ""
		if len(kv) == 2 {
			val = kv[1]
		}
		// No unescape implemented; good enough for 'time' and 'batch'
		out[key] = val
	}
	return out
}