package mention

import (
	"bytes"
	"strings"

	"github.com/diamondburned/arikawa/v2/discord"
	"github.com/diamondburned/arikawa/v2/gateway"
	"github.com/diamondburned/arikawa/v2/state/store"
	"github.com/diamondburned/cchat-discord/internal/segments/colored"
	"github.com/diamondburned/cchat-discord/internal/segments/inline"
	"github.com/diamondburned/cchat-discord/internal/segments/segutil"
	"github.com/diamondburned/cchat-discord/internal/urlutils"
	"github.com/diamondburned/cchat/text"
	"github.com/diamondburned/cchat/utils/empty"
	"github.com/diamondburned/ningen/v2"
)

// NameSegment represents a clickable member name.
type NameSegment struct {
	empty.TextSegment
	start int
	end   int
	um    User
}

var _ text.Segment = (*NameSegment)(nil)

func NewSegment(start, end int, user *User) NameSegment {
	return NameSegment{
		start: start,
		end:   end,
		um:    *user,
	}
}

func (m NameSegment) Bounds() (start, end int) {
	return m.start, m.end
}

func (m NameSegment) AsMentioner() text.Mentioner { return &m.um }
func (m NameSegment) AsAvatarer() text.Avatarer   { return &m.um }

// AsColorer only returns User if the user actually has a colored role.
func (m NameSegment) AsColorer() text.Colorer {
	if m.um.HasColor() {
		return &m.um
	}
	return nil
}

type User struct {
	user    discord.User
	guildID discord.GuildID

	store  store.Cabinet
	ningen *ningen.State

	// optional prefetching

	guild    *discord.Guild
	member   *discord.Member
	presence *gateway.Presence

	color        uint32
	hasColor     bool
	fetchedColor bool
}

var (
	_ text.Colorer   = (*User)(nil)
	_ text.Avatarer  = (*User)(nil)
	_ text.Mentioner = (*User)(nil)
)

// NewUser creates a new user mention.
func NewUser(u discord.User) *User {
	return &User{
		user:  u,
		store: store.NoopCabinet,
	}
}

// User returns the internal user.
func (um *User) User() discord.User {
	return um.user
}

// UserID returns the user ID.
func (um *User) UserID() discord.UserID {
	return um.user.ID
}

// SetGuildID sets the user's guild ID.
func (um *User) WithGuildID(guildID discord.GuildID) {
	um.guildID = guildID
}

// WithGuild sets the user's guild.
func (um *User) WithGuild(guild discord.Guild) {
	um.guildID = guild.ID
	um.guild = &guild
}

// WithMember sets the internal member to reduce roundtrips or cache hits. m can
// be nil.
func (um *User) WithMember(m discord.Member) {
	um.member = &m
}

// WithPresence sets the internal presence to reduce roundtrips or cache hits.
func (um *User) WithPresence(p gateway.Presence) {
	um.presence = &p
}

// WithState sets the internal state for usage.
func (um *User) WithState(state *ningen.State) {
	um.ningen = state
	um.store = state.Cabinet
}

// Prefetch prefetches everything in User.
func (um *User) Prefetch() {
	um.HasColor()
	um.getPresence()
}

// DisplayName returns either the nickname or the username.
func (um *User) DisplayName() string {
	if um.guildID.IsValid() {
		m, err := um.store.Member(um.guildID, um.user.ID)
		if err == nil && m.Nick != "" {
			return m.Nick
		}
	}

	return um.user.Username
}

// HasColor returns true if the current user has a color.
func (um *User) HasColor() bool {
	if um.fetchedColor {
		return um.hasColor
	}

	// We don't have any member color if we have neither the member nor guild.
	if !um.guildID.IsValid() || !um.user.ID.IsValid() {
		um.fetchedColor = true
		return false
	}

	// We do have a valid GuildID, but the store might be a Noop, so we
	// shouldn't mark it as fetched.
	guild := um.getGuild()
	member := um.getMember()

	if guild == nil || member == nil {
		return false
	}

	um.fetchedColor = true
	um.color, um.hasColor = MemberColor(*guild, *member)

	return um.hasColor
}

func (um *User) Color() uint32 {
	if um.HasColor() {
		return text.SolidColor(um.color)
	}

	return colored.Blurple
}

func (um *User) AvatarSize() int {
	return 96
}

func (um *User) AvatarText() string {
	return um.DisplayName()
}

func (um *User) Avatar() (url string) {
	return urlutils.AvatarURL(um.user.AvatarURL())
}

func (um *User) MentionInfo() text.Rich {
	var content bytes.Buffer
	var segment text.Rich

	content.WriteString("Username: ")
	content.WriteString(um.user.Username)
	content.WriteByte('#')
	content.WriteString(um.user.Discriminator)
	content.WriteString("\n\n")

	// Write extra information if any, but only if we have the guild state.
	if um.guildID.IsValid() {
		guild := um.getGuild()
		member := um.getMember()

		if guild != nil && member != nil {
			// Write a prepended new line, as role writes will always prepend a
			// new line. This is to prevent a trailing new line.
			formatSectionf(&segment, &content, "Roles")

			for _, id := range member.RoleIDs {
				rl, ok := findRole(guild.Roles, id)
				if !ok {
					continue
				}

				// Prepend a new line before each item.
				content.WriteByte('\n')
				// Write exactly the role name, then grab the segment and color
				// it.
				start, end := segutil.WriteStringBuf(&content, "@"+rl.Name)
				// But we only add the color if the role has one.
				if rgb := rl.Color.Uint32(); rgb > 0 {
					segutil.Add(&segment, colored.NewSegment(start, end, rgb))
				}
			}

			// End section.
			content.WriteString("\n\n")
		}
	}

	// Does the user have rich presence? If so, write.
	if p := um.getPresence(); p != nil {
		for _, ac := range p.Activities {
			formatActivity(&segment, &content, ac)
			content.WriteString("\n\n")
		}
	}

	// These information can only be obtained from the state. As such, we check
	// if the state is given.
	if um.ningen != nil {
		// Write the user's note if any.
		formatSectionf(&segment, &content, "Note")
		content.WriteRune('\n')

		if note := um.ningen.NoteState.Note(um.user.ID); note != "" {
			start, end := segutil.WriteStringBuf(&content, note)
			segutil.Add(&segment, inline.NewSegment(start, end, text.AttributeMonospace))
		} else {
			start, end := segutil.WriteStringBuf(&content, "empty")
			segutil.Add(&segment, inline.NewSegment(start, end, text.AttributeDimmed))
		}

		content.WriteString("\n\n")
	}

	// Assign the written content into the text segment and return it after
	// trimming the trailing new line.
	segment.Content = strings.TrimSuffix(content.String(), "\n")
	return segment
}

func (um *User) getGuild() *discord.Guild {
	if um.guild != nil {
		return um.guild
	}

	g, err := um.store.Guild(um.guildID)
	if err != nil {
		return nil
	}

	um.guild = g
	return g
}

func (um *User) getMember() *discord.Member {
	if !um.guildID.IsValid() {
		return nil
	}

	if um.member != nil {
		return um.member
	}

	m, err := um.store.Member(um.guildID, um.user.ID)
	if err != nil {
		if um.ningen != nil {
			um.ningen.MemberState.RequestMember(um.guildID, um.user.ID)
		}

		return nil
	}

	um.member = m
	return m
}

func (um *User) getPresence() *gateway.Presence {
	if um.presence != nil {
		return um.presence
	}

	p, err := um.store.Presence(um.guildID, um.user.ID)
	if err != nil {
		if um.guildID.IsValid() && um.ningen != nil {
			um.ningen.MemberState.RequestMember(um.guildID, um.user.ID)
		}

		return nil
	}

	um.presence = p
	return p
}