// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.

import {createSelector} from 'reselect';

import {General, Preferences} from '../../constants';

import {getConfig, getLicense} from 'selectors/entities/general';
import {getCurrentTeamId} from 'selectors/entities/teams';

import {PreferenceType, Theme} from 'types/preferences';
import {UserProfile} from 'types/users';
import {GlobalState} from 'types/store';
import {$ID} from 'types/utilities';

import {createShallowSelector} from 'utils/helpers';
import {getPreferenceKey} from 'utils/preference_utils';

export function getMyPreferences(state: GlobalState) {
    return state.entities.preferences.myPreferences;
}

export function get(state: GlobalState, category: string, name: string, defaultValue: any = '') {
    const key = getPreferenceKey(category, name);
    const prefs = getMyPreferences(state);

    if (!(key in prefs)) {
        return defaultValue;
    }

    return prefs[key].value;
}

export function getBool(state: GlobalState, category: string, name: string, defaultValue = false) {
    const value = get(state, category, name, String(defaultValue));
    return value !== 'false';
}

export function getInt(state: GlobalState, category: string, name: string, defaultValue = 0) {
    const value = get(state, category, name, defaultValue);
    return parseInt(value, 10);
}

export function makeGetCategory(): (state: GlobalState, category: string) => PreferenceType[] {
    return createSelector(
        getMyPreferences,
        (state: GlobalState, category: string) => category,
        (preferences, category) => {
            const prefix = category + '--';
            const prefsInCategory: PreferenceType[] = [];

            for (const key in preferences) {
                if (key.startsWith(prefix)) {
                    prefsInCategory.push(preferences[key]);
                }
            }

            return prefsInCategory;
        },
    );
}

const getDirectShowCategory = makeGetCategory();

export function getDirectShowPreferences(state: GlobalState) {
    return getDirectShowCategory(state, Preferences.CATEGORY_DIRECT_CHANNEL_SHOW);
}

const getGroupShowCategory = makeGetCategory();

export function getGroupShowPreferences(state: GlobalState) {
    return getGroupShowCategory(state, Preferences.CATEGORY_GROUP_CHANNEL_SHOW);
}

const getFavoritesCategory = makeGetCategory();

export function getFavoritesPreferences(state: GlobalState) {
    const favorites = getFavoritesCategory(state, Preferences.CATEGORY_FAVORITE_CHANNEL);
    return favorites.filter((f) => f.value === 'true').map((f) => f.name);
}

export const getVisibleTeammate: (state: GlobalState) => Array<$ID<UserProfile>> = createSelector(
    getDirectShowPreferences,
    (direct) => {
        return direct.filter((dm) => dm.value === 'true' && dm.name).map((dm) => dm.name);
    },
);

export const getVisibleGroupIds: (state: GlobalState) => string[] = createSelector(
    getGroupShowPreferences,
    (groups) => {
        return groups.filter((dm) => dm.value === 'true' && dm.name).map((dm) => dm.name);
    },
);

export const getTeammateNameDisplaySetting: (state: GlobalState) => string | undefined = createSelector(
    getConfig,
    getMyPreferences,
    getLicense,
    (config, preferences, license) => {
        const useAdminTeammateNameDisplaySetting = (license && license.LockTeammateNameDisplay === 'true') && config.LockTeammateNameDisplay === 'true';
        const key = getPreferenceKey(Preferences.CATEGORY_DISPLAY_SETTINGS, Preferences.NAME_NAME_FORMAT);
        if (preferences[key] && !useAdminTeammateNameDisplaySetting) {
            return preferences[key].value;
        } else if (config.TeammateNameDisplay) {
            return config.TeammateNameDisplay;
        }
        return General.TEAMMATE_NAME_DISPLAY.SHOW_USERNAME;
    },
);

const getThemePreference = createSelector(
    getMyPreferences,
    getCurrentTeamId,
    (myPreferences, currentTeamId) => {
        // Prefer the user's current team-specific theme over the user's current global theme
        let themePreference;

        if (currentTeamId) {
            themePreference = myPreferences[getPreferenceKey(Preferences.CATEGORY_THEME, currentTeamId)];
        }

        if (!themePreference) {
            themePreference = myPreferences[getPreferenceKey(Preferences.CATEGORY_THEME, '')];
        }

        return themePreference;
    },
);

const getDefaultTheme = createSelector(getConfig, (config): Theme => {
    if (config.DefaultTheme && config.DefaultTheme in Preferences.THEMES) {
        const theme: Theme = Preferences.THEMES[config.DefaultTheme];
        if (theme) {
            return theme;
        }
    }

    // If no config.DefaultTheme or value doesn't refer to a valid theme name...
    return Preferences.THEMES.default;
});

export const getTheme: (state: GlobalState) => Theme = createShallowSelector(
    getThemePreference,
    getDefaultTheme,
    (themePreference, defaultTheme): Theme => {
        const themeValue: Theme | string = themePreference?.value ?? defaultTheme;

        // A custom theme will be a JSON-serialized object stored in a preference
        // At this point, the theme should be a plain object
        const theme: Theme = typeof themeValue === 'string' ? JSON.parse(themeValue) : themeValue;

        // If this is a system theme, find it in case the user's theme is missing any fields
        if (theme.type && theme.type !== 'custom') {
            const match = Object.values(Preferences.THEMES).find((v) => v.type === theme.type);
            if (match) {
                if (!match.mentionBg) {
                    match.mentionBg = match.mentionBj;
                }

                return match;
            }
        }

        for (const key of Object.keys(defaultTheme)) {
            if (theme[key]) {
                // Fix a case where upper case theme colours are rendered as black
                theme[key] = theme[key]?.toLowerCase();
            }
        }

        // Backwards compatability with old name
        if (!theme.mentionBg) {
            theme.mentionBg = theme.mentionBj;
        }

        return Object.assign({}, defaultTheme, theme);
    },
);

export function makeGetStyleFromTheme<Style>(): (state: GlobalState, getStyleFromTheme: (theme: Theme) => Style) => Style {
    return createSelector(
        getTheme,
        (state: GlobalState, getStyleFromTheme: (theme: Theme) => Style) => getStyleFromTheme,
        (theme, getStyleFromTheme) => {
            return getStyleFromTheme(theme);
        },
    );
}

export type SidebarPreferences = {
    grouping: 'by_type' | 'none';
    unreads_at_top: 'true' | 'false';
    favorite_at_top: 'true' | 'false';
    sorting: 'alpha' | 'recent';
}

const defaultSidebarPrefs: SidebarPreferences = {
    grouping: 'by_type',
    unreads_at_top: 'true',
    favorite_at_top: 'true',
    sorting: 'alpha',
};

export const getSidebarPreferences: (state: GlobalState) => SidebarPreferences = createSelector(
    (state: GlobalState) => {
        const config = getConfig(state);
        return config.ExperimentalGroupUnreadChannels !== General.DISABLED && getBool(
            state,
            Preferences.CATEGORY_SIDEBAR_SETTINGS,
            'show_unread_section',
            config.ExperimentalGroupUnreadChannels === General.DEFAULT_ON,
        );
    },
    (state) => {
        return get(
            state,
            Preferences.CATEGORY_SIDEBAR_SETTINGS,
            '',
            null,
        );
    },
    (showUnreadSection, sidebarPreference) => {
        let sidebarPrefs = JSON.parse(sidebarPreference);
        if (sidebarPrefs === null) {
            // Support unread settings for old implementation
            sidebarPrefs = {
                ...defaultSidebarPrefs,
                unreads_at_top: showUnreadSection ? 'true' : 'false',
            };
        }

        return sidebarPrefs;
    },
);

// shouldShowUnreadsCategory returns true if the user has unereads grouped separately with the new sidebar enabled.
export const shouldShowUnreadsCategory: (state: GlobalState) => boolean = createSelector(
    (state: GlobalState) => get(state, Preferences.CATEGORY_SIDEBAR_SETTINGS, Preferences.SHOW_UNREAD_SECTION),
    (state: GlobalState) => get(state, Preferences.CATEGORY_SIDEBAR_SETTINGS, ''),
    (state: GlobalState) => getConfig(state).ExperimentalGroupUnreadChannels,
    (userPreference, oldUserPreference, serverDefault) => {
        // Prefer the show_unread_section user preference over the previous version
        if (userPreference) {
            return userPreference === 'true';
        }

        if (oldUserPreference) {
            return JSON.parse(oldUserPreference).unreads_at_top === 'true';
        }

        // The user setting is not set, so use the system default
        return serverDefault === General.DEFAULT_ON;
    },
);

export function shouldAutocloseDMs(state: GlobalState) {
    const config = getConfig(state);
    if (!config.CloseUnusedDirectMessages || config.CloseUnusedDirectMessages === 'false') {
        return false;
    }

    const preference = get(state, Preferences.CATEGORY_SIDEBAR_SETTINGS, Preferences.CHANNEL_SIDEBAR_AUTOCLOSE_DMS, Preferences.AUTOCLOSE_DMS_ENABLED);
    return preference === Preferences.AUTOCLOSE_DMS_ENABLED;
}