package api

import (
	"io"

	"git.sr.ht/~diamondburned/arikawa/discord"
	"git.sr.ht/~diamondburned/arikawa/httputil"
	"github.com/pkg/errors"
)

type Message struct {
	ID        discord.Snowflake `json:"id"`
	Type      MessageType       `json:"type"`
	ChannelID discord.Snowflake `json:"channel_id"`
	GuildID   discord.Snowflake `json:"guild_id,omitempty"`

	// The author object follows the structure of the user object, but is only
	// a valid user in the case where the message is generated by a user or bot
	// user. If the message is generated by a webhook, the author object
	// corresponds to the webhook's id, username, and avatar. You can tell if a
	// message is generated by a webhook by checking for the webhook_id on the
	// message object.
	Author User `json:"author"`

	// The member object exists in MESSAGE_CREATE and MESSAGE_UPDATE
	// events from text-based guild channels.
	Member *GuildMember `json:"member,omitempty"`

	Content string `json:"content"`

	Timestamp       discord.Timestamp  `json:"timestamp,omitempty"`
	EditedTimestamp *discord.Timestamp `json:"edited_timestamp,omitempty"`

	TTS    bool `json:"tts"`
	Pinned bool `json:"pinned"`

	// The user objects in the mentions array will only have the partial
	// member field present in MESSAGE_CREATE and MESSAGE_UPDATE events from
	// text-based guild channels.
	Mentions []GuildUser `json:"mentions"`

	MentionRoleIDs  []discord.Snowflake `json:"mention_roles"`
	MentionEveryone bool                `json:"mention_everyone"`

	// Not all channel mentions in a message will appear in mention_channels.
	MentionChannels []ChannelMention `json:"mention_channels,omitempty"`

	Attachments []Attachment `json:"attachments"`
	Embeds      []Embed      `json:"embeds"`

	Reactions []Reaction `json:"reaction,omitempty"`

	// Used for validating a message was sent
	Nonce string `json:"nonce,omitempty"`

	WebhookID   discord.Snowflake   `json:"webhook_id,omitempty"`
	Activity    *MessageActivity    `json:"activity,omitempty"`
	Application *MessageApplication `json:"application,omitempty"`
	Reference   *MessageReference   `json:"message_reference,omitempty"`
	Flags       MessageFlags        `json:"flags"`
}

type MessageType uint8

const (
	DefaultMessage MessageType = iota
	RecipientAddMessage
	RecipientRemoveMessage
	CallMessage
	ChannelNameChangeMessage
	ChannelIconChangeMessage
	ChannelPinnedMessage
	GuildMemberJoinMessage
	NitroBoostMessage
	NitroTier1Message
	NitroTier2Message
	NitroTier3Message
	ChannelFollowAddMessage
)

type MessageFlags uint8

const (
	CrosspostedMessage MessageFlags = 1 << iota
	MessageIsCrosspost
	SuppressEmbeds
	SourceMessageDeleted
	UrgentMessage
)

type ChannelMention struct {
	ChannelID   discord.Snowflake `json:"id"`
	GuildID     discord.Snowflake `json:"guild_id"`
	ChannelType ChannelType       `json:"type"`
	ChannelName string            `json:"name"`
}

type GuildUser struct {
	User
	Member *GuildMember `json:"member,omitempty"`
}

//

type MessageActivity struct {
	Type MessageActivityType `json:"type"`

	// From a Rich Presence event
	PartyID string `json:"party_id,omitempty"`
}

type MessageActivityType uint8

const (
	JoinMessage MessageActivityType = iota + 1
	SpectateMessage
	ListenMessage
	JoinRequestMessage
)

//

type MessageApplication struct {
	ID          discord.Snowflake `json:"id"`
	CoverID     string            `json:"cover_image,omitempty"`
	Description string            `json:"description"`
	Icon        string            `json:"icon"`
	Name        string            `json:"name"`
}

//

type MessageReference struct {
	ChannelID discord.Snowflake `json:"channel_id"`

	// Field might not be provided
	MessageID discord.Snowflake `json:"message_id,omitempty"`
	GuildID   discord.Snowflake `json:"guild_id,omitempty"`
}

//

type Attachment struct {
	ID       discord.Snowflake `json:"id"`
	Filename string            `json:"filename"`
	Size     uint64            `json:"size"`

	URL   discord.URL `json:"url"`
	Proxy discord.URL `json:"proxy_url"`

	// Only if Image
	Height uint `json:"height,omitempty"`
	Width  uint `json:"width,omitempty"`
}

//

func (c *Client) Messages(
	channelID discord.Snowflake, limit uint) ([]Message, error) {

	return c.messages(channelID, limit, nil)
}

func (c *Client) MessagesAround(
	channelID, around discord.Snowflake, limit uint) ([]Message, error) {

	return c.messages(channelID, limit, map[string]interface{}{
		"around": around,
	})
}

func (c *Client) MessagesBefore(
	channelID, before discord.Snowflake, limit uint) ([]Message, error) {

	return c.messages(channelID, limit, map[string]interface{}{
		"before": before,
	})
}

func (c *Client) MessagesAfter(
	channelID, after discord.Snowflake, limit uint) ([]Message, error) {

	return c.messages(channelID, limit, map[string]interface{}{
		"after": after,
	})
}

func (c *Client) messages(channelID discord.Snowflake,
	limit uint, body map[string]interface{}) ([]Message, error) {

	if body == nil {
		body = map[string]interface{}{}
	}

	switch {
	case limit == 0:
		limit = 50
	case limit > 100:
		limit = 100
	}

	body["limit"] = limit

	var msgs []Message
	return msgs, c.RequestJSON(&msgs, "GET",
		EndpointChannels+channelID.String(), httputil.WithJSONBody(c, body))
}

func (c *Client) Message(
	channelID, messageID discord.Snowflake) (*Message, error) {

	var msg *Message
	return msg, c.RequestJSON(&msg, "GET",
		EndpointChannels+channelID.String()+"/messages/"+messageID.String())
}

func (c *Client) SendMessage(channelID discord.Snowflake,
	content string, embed *Embed) (*Message, error) {

	return c.SendMessageComplex(channelID, SendMessageData{
		Content: content,
		Embed:   embed,
	})
}

func (c *Client) SendMessageComplex(channelID discord.Snowflake,
	data SendMessageData) (*Message, error) {

	if data.Embed != nil {
		if err := data.Embed.Validate(); err != nil {
			return nil, errors.Wrap(err, "Embed error")
		}
	}

	var URL = EndpointChannels + channelID.String()
	var msg *Message

	if len(data.Files) == 0 {
		// No files, no need for streaming
		return msg, c.RequestJSON(&msg, "POST", URL,
			httputil.WithJSONBody(c, data))
	}

	writer := func(w io.Writer) error {
		return data.WriteMultipart(c, w)
	}

	resp, err := c.MeanwhileBody(writer, "POST", URL)
	if err != nil {
		return nil, err
	}

	defer resp.Body.Close()

	return msg, c.DecodeStream(resp.Body, &msg)
}

func (c *Client) EditMessage(channelID, messageID discord.Snowflake,
	content string, embed *Embed, suppressEmbeds bool) (*Message, error) {

	var param struct {
		Content string       `json:"content,omitempty"`
		Embed   *Embed       `json:"embed,omitempty"`
		Flags   MessageFlags `json:"flags,omitempty"`
	}

	param.Content = content
	param.Embed = embed
	if suppressEmbeds {
		param.Flags = SuppressEmbeds
	}

	var msg *Message
	return msg, c.RequestJSON(
		&msg, "PATCH",
		EndpointChannels+channelID.String()+"/messages/"+messageID.String(),
		httputil.WithJSONBody(c, param),
	)
}

// DeleteMessage deletes a message. Requires MANAGE_MESSAGES if the message is
// not made by yourself.
func (c *Client) DeleteMessage(channelID, messageID discord.Snowflake) error {
	return c.FastRequest("DELETE", EndpointChannels+channelID.String()+
		"/messages/"+messageID.String())
}

// DeleteMessages only works for bots. It can't delete messages older than 2
// weeks, and will fail if tried. This endpoint requires MANAGE_MESSAGES.
func (c *Client) DeleteMessages(channelID discord.Snowflake,
	messageIDs []discord.Snowflake) error {

	var param struct {
		Messages []discord.Snowflake `json:"messages"`
	}

	param.Messages = messageIDs

	return c.FastRequest("POST", EndpointChannels+channelID.String()+
		"/messages/bulk-delete", httputil.WithJSONBody(c, param))
}