package cozy

import (
	"github.com/diamondburned/cchat"
	"github.com/diamondburned/cchat-gtk/internal/gts"
	"github.com/diamondburned/cchat-gtk/internal/ui/messages/container"
	"github.com/diamondburned/cchat-gtk/internal/ui/messages/input"
	"github.com/diamondburned/cchat-gtk/internal/ui/messages/message"
	"github.com/diamondburned/cchat-gtk/internal/ui/primitives"
)

// Unwrapper provides an interface for messages to be unwrapped. This is used to
// convert between collapsed and full messages.
type Unwrapper interface {
	Unwrap() *message.GenericContainer
}

var (
	_ Unwrapper = (*CollapsedMessage)(nil)
	_ Unwrapper = (*CollapsedSendingMessage)(nil)
	_ Unwrapper = (*FullMessage)(nil)
	_ Unwrapper = (*FullSendingMessage)(nil)
)

// Collapsible is an interface for cozy messages to return whether or not
// they're full or collapsed.
type Collapsible interface {
	// Compact returns true if the message is a compact one and not full.
	Collapsed() bool
}

var (
	_ Collapsible = (*CollapsedMessage)(nil)
	_ Collapsible = (*CollapsedSendingMessage)(nil)
	_ Collapsible = (*FullMessage)(nil)
	_ Collapsible = (*FullSendingMessage)(nil)
)

const (
	AvatarSize   = 40
	AvatarMargin = 10
)

type Container struct {
	*container.ListContainer
}

func NewContainer(ctrl container.Controller) *Container {
	c := &Container{}
	c.ListContainer = container.NewListContainer(c, ctrl)

	primitives.AddClass(c, "cozy-container")
	return c
}

func (c *Container) NewMessage(msg cchat.MessageCreate) container.MessageRow {
	// We're not checking for a collapsed message here anymore, as the
	// CreateMessage method will do that.

	// // Is the latest message of the same author? If yes, display it as a
	// // collapsed message.
	// if c.lastMessageIsAuthor(msg.Author().ID()) {
	// 	return NewCollapsedMessage(msg)
	// }

	full := NewFullMessage(msg)
	author := msg.Author()

	// Try and reuse an existing avatar if the author has one.
	if avatarURL := author.Avatar(); avatarURL != "" {
		// Try reusing the avatar, but fetch it from the interndet if we can't
		// reuse. The reuse function does this for us.
		c.reuseAvatar(author.ID(), author.Avatar(), full)
	}

	return full
}

func (c *Container) NewPresendMessage(msg input.PresendMessage) container.PresendMessageRow {
	// We can do the check here since we're never using NewPresendMessage for
	// backlog messages.
	if c.lastMessageIsAuthor(msg.AuthorID(), msg.Author().String(), 0) {
		return NewCollapsedSendingMessage(msg)
	}

	full := NewFullSendingMessage(msg)

	// Try and see if we can reuse the avatar, and fallback if possible. The
	// avatar URL passed in here will always yield an equal.
	c.reuseAvatar(msg.AuthorID(), msg.AuthorAvatarURL(), &full.FullMessage)

	return full
}

func (c *Container) findAuthorID(authorID string) container.MessageRow {
	// Search the old author if we have any.
	return c.ListStore.FindMessage(func(msgc container.MessageRow) bool {
		return msgc.AuthorID() == authorID
	})
}

// reuseAvatar tries to search past messages with the same author ID and URL for
// the image. It will fetch anew if there's none.
func (c *Container) reuseAvatar(authorID, avatarURL string, full *FullMessage) {
	// Is this a message that we can work with? We have to assert to
	// FullSendingMessage because that's where our messages are.
	var lastAuthorMsg = c.findAuthorID(authorID)

	// Borrow the avatar pixbuf, but only if the avatar URL is the same.
	p, ok := lastAuthorMsg.(AvatarPixbufCopier)
	if ok && lastAuthorMsg.AvatarURL() == avatarURL {
		p.CopyAvatarPixbuf(full.Avatar.Image)
		full.Avatar.ManuallySetURL(avatarURL)
	} else {
		// We can't borrow, so we need to fetch it anew.
		full.Avatar.SetURL(avatarURL)
	}
}

func (c *Container) lastMessageIsAuthor(id cchat.ID, name string, offset int) bool {
	// Get the offfsetth message from last.
	var last = c.ListStore.NthMessage((c.ListStore.MessagesLen() - 1) + offset)
	return gridMessageIsAuthor(last, id, name)
}

func gridMessageIsAuthor(gridMsg container.MessageRow, id cchat.ID, name string) bool {
	return gridMsg != nil &&
		gridMsg.AuthorID() == id &&
		gridMsg.AuthorName() == name
}

func (c *Container) CreateMessage(msg cchat.MessageCreate) {
	gts.ExecAsync(func() {
		// Create the message in the parent's handler. This handler will also
		// wipe old messages.
		c.ListContainer.CreateMessageUnsafe(msg)

		// Did the handler wipe old messages? It will only do so if the user is
		// scrolled to the bottom.
		if c.ListContainer.CleanMessages() {
			// We need to uncollapse the first (top) message. No length check is
			// needed here, as we just inserted a message.
			c.uncompact(c.FirstMessage())
		}

		switch msg.ID() {
		// Should we collapse this message? Yes, if the current message is
		// inserted at the end and its author is the same as the last author.
		case c.ListContainer.LastMessage().ID():
			author := msg.Author()
			if c.lastMessageIsAuthor(author.ID(), author.Name().String(), -1) {
				c.compact(c.ListContainer.LastMessage())
			}

		// If we've prepended the message, then see if we need to collapse the
		// second message.
		case c.ListContainer.FirstMessage().ID():
			if sec := c.NthMessage(1); sec != nil {
				// The author is the same; collapse.
				author := msg.Author()
				if gridMessageIsAuthor(sec, author.ID(), author.Name().String()) {
					c.compact(sec)
				}
			}
		}
	})
}

func (c *Container) UpdateMessage(msg cchat.MessageUpdate) {
	gts.ExecAsync(func() {
		c.UpdateMessageUnsafe(msg)
	})
}

func (c *Container) DeleteMessage(msg cchat.MessageDelete) {
	gts.ExecAsync(func() {
		// Get the previous and next message before deleting. We'll need them to
		// evaluate whether we need to change anything.
		prev, next := c.ListStore.Around(msg.ID())

		// The function doesn't actually try and re-collapse the bottom message
		// when a sandwiched message is deleted. This is fine.

		// Delete the message off of the parent's container.
		msg := c.ListStore.PopMessage(msg.ID())

		// Don't calculate if we don't have any messages, or no messages before
		// and after.
		if c.ListStore.MessagesLen() == 0 || prev == nil || next == nil {
			return
		}

		// Check if the last message is the author's (relative to i):
		if prev.AuthorID() == msg.AuthorID() {
			// If the author is the same, then we don't need to uncollapse the
			// message.
			return
		}

		// If the next message (relative to i) is not the deleted message's
		// author, then we don't need to uncollapse it.
		if next.AuthorID() != msg.AuthorID() {
			return
		}

		// Uncompact or turn the message to a full one.
		c.uncompact(next)
	})
}

func (c *Container) uncompact(msg container.MessageRow) {
	// We should only uncompact the message if it's compacted in the first
	// place.
	if collapse, ok := msg.(Collapsible); !ok || !collapse.Collapsed() {
		return
	}

	// We can't unwrap if the message doesn't implement Unwrapper.
	uw, ok := msg.(Unwrapper)
	if !ok {
		return
	}

	// Start the "lengthy" uncollapse process.
	full := WrapFullMessage(uw.Unwrap())
	// Update the container to reformat everything including the timestamps.
	message.RefreshContainer(full, full.GenericContainer)
	// Update the avatar if needed be, since we're now showing it.
	c.reuseAvatar(msg.AuthorID(), msg.AvatarURL(), full)

	// Swap the old next message out for a new one.
	c.ListStore.SwapMessage(full)
}

func (c *Container) compact(msg container.MessageRow) {
	// Exit if the message is already collapsed.
	if collapse, ok := msg.(Collapsible); !ok || collapse.Collapsed() {
		return
	}

	uw, ok := msg.(Unwrapper)
	if !ok {
		return
	}

	compact := WrapCollapsedMessage(uw.Unwrap())
	message.RefreshContainer(compact, compact.GenericContainer)

	c.ListStore.SwapMessage(compact)
}