package pluginapi

import (
	"net/http"
	"time"

	"github.com/pkg/errors"

	"github.com/mattermost/mattermost/server/public/model"
	"github.com/mattermost/mattermost/server/public/plugin"
)

// ChannelService exposes methods to manipulate channels.
type ChannelService struct {
	api plugin.API
}

// Get gets a channel.
//
// Minimum server version: 5.2
func (c *ChannelService) Get(channelID string) (*model.Channel, error) {
	channel, appErr := c.api.GetChannel(channelID)

	return channel, normalizeAppErr(appErr)
}

// GetByName gets a channel by its name, given a team id.
//
// Minimum server version: 5.2
func (c *ChannelService) GetByName(teamID, channelName string, includeDeleted bool) (*model.Channel, error) {
	channel, appErr := c.api.GetChannelByName(teamID, channelName, includeDeleted)

	return channel, normalizeAppErr(appErr)
}

// GetDirect gets a direct message channel.
//
// Note that if the channel does not exist it will create it.
//
// Minimum server version: 5.2
func (c *ChannelService) GetDirect(userID1, userID2 string) (*model.Channel, error) {
	channel, appErr := c.api.GetDirectChannel(userID1, userID2)

	return channel, normalizeAppErr(appErr)
}

// GetGroup gets a group message channel.
//
// Note that if the channel does not exist it will create it.
//
// Minimum server version: 5.2
func (c *ChannelService) GetGroup(userIDs []string) (*model.Channel, error) {
	channel, appErr := c.api.GetGroupChannel(userIDs)

	return channel, normalizeAppErr(appErr)
}

// GetByNameForTeamName gets a channel by its name, given a team name.
//
// Minimum server version: 5.2
func (c *ChannelService) GetByNameForTeamName(teamName, channelName string, includeDeleted bool) (*model.Channel, error) {
	channel, appErr := c.api.GetChannelByNameForTeamName(teamName, channelName, includeDeleted)

	return channel, normalizeAppErr(appErr)
}

// ListForTeamForUser gets a list of channels for given user ID in given team ID.
//
// Minimum server version: 5.6
func (c *ChannelService) ListForTeamForUser(teamID, userID string, includeDeleted bool) ([]*model.Channel, error) {
	channels, appErr := c.api.GetChannelsForTeamForUser(teamID, userID, includeDeleted)

	return channels, normalizeAppErr(appErr)
}

// ListPublicChannelsForTeam gets a list of all channels.
//
// Minimum server version: 5.2
func (c *ChannelService) ListPublicChannelsForTeam(teamID string, page, perPage int) ([]*model.Channel, error) {
	channels, appErr := c.api.GetPublicChannelsForTeam(teamID, page, perPage)

	return channels, normalizeAppErr(appErr)
}

// Search returns the channels on a team matching the provided search term.
//
// Minimum server version: 5.6
func (c *ChannelService) Search(teamID, term string) ([]*model.Channel, error) {
	channels, appErr := c.api.SearchChannels(teamID, term)

	return channels, normalizeAppErr(appErr)
}

// Create creates a channel.
//
// Minimum server version: 5.2
func (c *ChannelService) Create(channel *model.Channel) error {
	createdChannel, appErr := c.api.CreateChannel(channel)
	if appErr != nil {
		return normalizeAppErr(appErr)
	}

	*channel = *createdChannel

	return c.waitForChannelCreation(channel.Id)
}

// Update updates a channel.
//
// Minimum server version: 5.2
func (c *ChannelService) Update(channel *model.Channel) error {
	updatedChannel, appErr := c.api.UpdateChannel(channel)
	if appErr != nil {
		return normalizeAppErr(appErr)
	}

	*channel = *updatedChannel

	return nil
}

// Delete deletes a channel.
//
// Minimum server version: 5.2
func (c *ChannelService) Delete(channelID string) error {
	return normalizeAppErr(c.api.DeleteChannel(channelID))
}

// GetChannelStats gets statistics for a channel.
//
// Minimum server version: 5.6
func (c *ChannelService) GetChannelStats(channelID string) (*model.ChannelStats, error) {
	channelStats, appErr := c.api.GetChannelStats(channelID)

	return channelStats, normalizeAppErr(appErr)
}

// GetMember gets a channel membership for a user.
//
// Minimum server version: 5.2
func (c *ChannelService) GetMember(channelID, userID string) (*model.ChannelMember, error) {
	channelMember, appErr := c.api.GetChannelMember(channelID, userID)

	return channelMember, normalizeAppErr(appErr)
}

// ListMembers gets a channel membership for all users.
//
// Minimum server version: 5.6
func (c *ChannelService) ListMembers(channelID string, page, perPage int) ([]*model.ChannelMember, error) {
	channelMembers, appErr := c.api.GetChannelMembers(channelID, page, perPage)

	return channelMembersToChannelMemberSlice(channelMembers), normalizeAppErr(appErr)
}

// ListMembersByIDs gets a channel membership for a particular User
//
// Minimum server version: 5.6
func (c *ChannelService) ListMembersByIDs(channelID string, userIDs []string) ([]*model.ChannelMember, error) {
	channelMembers, appErr := c.api.GetChannelMembersByIds(channelID, userIDs)

	return channelMembersToChannelMemberSlice(channelMembers), normalizeAppErr(appErr)
}

// ListMembersForUser returns all channel memberships on a team for a user.
//
// Minimum server version: 5.10
func (c *ChannelService) ListMembersForUser(teamID, userID string, page, perPage int) ([]*model.ChannelMember, error) {
	channelMembers, appErr := c.api.GetChannelMembersForUser(teamID, userID, page, perPage)

	return channelMembers, normalizeAppErr(appErr)
}

// AddMember joins a user to a channel (as if they joined themselves).
// This means the user will not receive notifications for joining the channel.
//
// Minimum server version: 5.2
func (c *ChannelService) AddMember(channelID, userID string) (*model.ChannelMember, error) {
	channelMember, appErr := c.api.AddChannelMember(channelID, userID)

	return channelMember, normalizeAppErr(appErr)
}

// AddUser adds a user to a channel as if the specified user had invited them.
// This means the user will receive the regular notifications for being added to the channel.
//
// Minimum server version: 5.18
func (c *ChannelService) AddUser(channelID, userID, asUserID string) (*model.ChannelMember, error) {
	channelMember, appErr := c.api.AddUserToChannel(channelID, userID, asUserID)

	return channelMember, normalizeAppErr(appErr)
}

// DeleteMember deletes a channel membership for a user.
//
// Minimum server version: 5.2
func (c *ChannelService) DeleteMember(channelID, userID string) error {
	appErr := c.api.DeleteChannelMember(channelID, userID)

	return normalizeAppErr(appErr)
}

// UpdateChannelMemberRoles updates a user's roles for a channel.
//
// Minimum server version: 5.2
func (c *ChannelService) UpdateChannelMemberRoles(channelID, userID, newRoles string) (*model.ChannelMember, error) {
	channelMember, appErr := c.api.UpdateChannelMemberRoles(channelID, userID, newRoles)

	return channelMember, normalizeAppErr(appErr)
}

// UpdateChannelMemberNotifications updates a user's notification properties for a channel.
//
// Minimum server version: 5.2
func (c *ChannelService) UpdateChannelMemberNotifications(channelID, userID string, notifications map[string]string) (*model.ChannelMember, error) {
	channelMember, appErr := c.api.UpdateChannelMemberNotifications(channelID, userID, notifications)

	return channelMember, normalizeAppErr(appErr)
}

// CreateSidebarCategory creates a new sidebar category for a set of channels.
//
// Minimum server version: 5.38
func (c *ChannelService) CreateSidebarCategory(
	userID, teamID string, newCategory *model.SidebarCategoryWithChannels) error {
	category, appErr := c.api.CreateChannelSidebarCategory(userID, teamID, newCategory)
	if appErr != nil {
		return normalizeAppErr(appErr)
	}
	*newCategory = *category

	return nil
}

// GetSidebarCategories returns sidebar categories.
//
// Minimum server version: 5.38
func (c *ChannelService) GetSidebarCategories(userID, teamID string) (*model.OrderedSidebarCategories, error) {
	categories, appErr := c.api.GetChannelSidebarCategories(userID, teamID)

	return categories, normalizeAppErr(appErr)
}

// UpdateSidebarCategories updates the channel sidebar categories.
//
// Minimum server version: 5.38
func (c *ChannelService) UpdateSidebarCategories(
	userID, teamID string, categories []*model.SidebarCategoryWithChannels) error {
	updatedCategories, appErr := c.api.UpdateChannelSidebarCategories(userID, teamID, categories)
	if appErr != nil {
		return normalizeAppErr(appErr)
	}
	copy(categories, updatedCategories)

	return nil
}

func (c *ChannelService) waitForChannelCreation(channelID string) error {
	if len(c.api.GetConfig().SqlSettings.DataSourceReplicas) == 0 {
		return nil
	}

	now := time.Now()

	for time.Since(now) < 1500*time.Millisecond {
		time.Sleep(100 * time.Millisecond)

		if _, err := c.api.GetChannel(channelID); err == nil {
			// Channel found
			return nil
		} else if err.StatusCode != http.StatusNotFound {
			return err
		}
	}

	return errors.Errorf("giving up waiting for channel creation, channelID=%s", channelID)
}

func channelMembersToChannelMemberSlice(cm model.ChannelMembers) []*model.ChannelMember {
	cmp := make([]*model.ChannelMember, len(cm))
	for i := range cm {
		cmp[i] = &(cm)[i]
	}

	return cmp
}