import { isMac, Key } from './Keyboard';
import SettingsStore from './settings/SettingsStore';

export enum KeyBindingContext {
    /** Key bindings for the chat message composer component */
    MessageComposer = 'MessageComposer',
    /** Key bindings for text editing autocompletion */
    AutoComplete = 'AutoComplete',
    /** Left room list sidebar */
    RoomList = 'RoomList',
    /** Current room view */
    Room = 'Room',
    /** Shortcuts to navigate do various menus / dialogs / screens */
    Navigation = 'Navigation',
}

export enum KeyAction {
    None = 'None',

    // SendMessageComposer actions:

    /** Send a message */
    Send = 'Send',
    /** Go backwards through the send history and use the message in composer view */
    SelectPrevSendHistory = 'SelectPrevSendHistory',
    /** Go forwards through the send history */
    SelectNextSendHistory = 'SelectNextSendHistory',
    /** Start editing the user's last sent message */
    EditPrevMessage = 'EditPrevMessage',
    /** Start editing the user's next sent message */
    EditNextMessage = 'EditNextMessage',
    /** Cancel editing a message or cancel replying to a message*/
    CancelEditing = 'CancelEditing',

    /** Set bold format the current selection */
    FormatBold = 'FormatBold',
    /** Set italics format the current selection */
    FormatItalics = 'FormatItalics',
    /** Format the current selection as quote */
    FormatQuote = 'FormatQuote',
    /** Undo the last editing */
    EditUndo = 'EditUndo',
    /** Redo editing */
    EditRedo = 'EditRedo',
    /** Insert new line */
    NewLine = 'NewLine',
    MoveCursorToStart = 'MoveCursorToStart',
    MoveCursorToEnd = 'MoveCursorToEnd',

    // Autocomplete

    /** Apply the current autocomplete selection */
    AutocompleteApply = 'AutocompleteApply',
    /** Cancel autocompletion */
    AutocompleteCancel = 'AutocompleteCancel',
    /** Move to the previous autocomplete selection */
    AutocompletePrevSelection = 'AutocompletePrevSelection',
    /** Move to the next autocomplete selection */
    AutocompleteNextSelection = 'AutocompleteNextSelection',

    // Room list

    /** Clear room list filter field */
    RoomListClearSearch = 'RoomListClearSearch',
    /** Navigate up/down in the room list */
    RoomListPrevRoom = 'RoomListPrevRoom',
    /** Navigate down in the room list */
    RoomListNextRoom = 'RoomListNextRoom',
    /** Select room from the room list */
    RoomListSelectRoom = 'RoomListSelectRoom',
    /** Collapse room list section */
    RoomListCollapseSection = 'RoomListCollapseSection',
    /** Expand room list section, if already expanded, jump to first room in the selection */
    RoomListExpandSection = 'RoomListExpandSection',

    // Room

    /** Jump to room search */
    RoomFocusRoomSearch = 'RoomFocusRoomSearch',
    /** Scroll up in the timeline */
    RoomScrollUp = 'RoomScrollUp',
    /** Scroll down in the timeline */
    RoomScrollDown = 'RoomScrollDown',
    /** Dismiss read marker and jump to bottom */
    RoomDismissReadMarker = 'RoomDismissReadMarker',
    /* Upload a file */
    RoomUploadFile = 'RoomUploadFile',
    /* Search (must be enabled) */
    RoomSearch = 'RoomSearch',
    /* Jump to the first (downloaded) message in the room */
    RoomJumpToFirstMessage = 'RoomJumpToFirstMessage',
    /* Jump to the latest message in the room */
    RoomJumpToLatestMessage = 'RoomJumpToLatestMessage',

    // Navigation

    /** Toggle the room side panel */
    NavToggleRoomSidePanel = 'NavToggleRoomSidePanel',
    /** Toggle the user menu */
    NavToggleUserMenu = 'NavToggleUserMenu',
    /* Toggle the short cut help dialog */
    NavToggleShortCutDialog = 'NavToggleShortCutDialog',
    /* Got to the Element home screen */
    NavGoToHome = 'NavGoToHome',
    /* Select prev room */
    NavSelectPrevRoom = 'NavSelectPrevRoom',
    /* Select next room */
    NavSelectNextRoom = 'NavSelectNextRoom',
    /* Select prev room with unread messages*/
    NavSelectPrevUnreadRoom = 'NavSelectPrevUnreadRoom',
    /* Select next room with unread messages*/
    NavSelectNextUnreadRoom = 'NavSelectNextUnreadRoom',
}

/**
 * Represent a key combination.
 *
 * The combo is evaluated strictly, i.e. the KeyboardEvent must match exactly what is specified in the KeyCombo.
 */
export type KeyCombo = {
    key?: string;

    /** On PC: ctrl is pressed; on Mac: meta is pressed */
    ctrlOrCmd?: boolean;

    altKey?: boolean;
    ctrlKey?: boolean;
    metaKey?: boolean;
    shiftKey?: boolean;
}

export type KeyBinding = {
    action: KeyAction;
    keyCombo: KeyCombo;
}

const messageComposerBindings = (): KeyBinding[] => {
    const bindings: KeyBinding[] = [
        {
            action: KeyAction.SelectPrevSendHistory,
            keyCombo: {
                key: Key.ARROW_UP,
                altKey: true,
                ctrlKey: true,
            },
        },
        {
            action: KeyAction.SelectNextSendHistory,
            keyCombo: {
                key: Key.ARROW_DOWN,
                altKey: true,
                ctrlKey: true,
            },
        },
        {
            action: KeyAction.EditPrevMessage,
            keyCombo: {
                key: Key.ARROW_UP,
            },
        },
        {
            action: KeyAction.EditNextMessage,
            keyCombo: {
                key: Key.ARROW_DOWN,
            },
        },
        {
            action: KeyAction.CancelEditing,
            keyCombo: {
                key: Key.ESCAPE,
            },
        },
        {
            action: KeyAction.FormatBold,
            keyCombo: {
                key: Key.B,
                ctrlOrCmd: true,
            },
        },
        {
            action: KeyAction.FormatItalics,
            keyCombo: {
                key: Key.I,
                ctrlOrCmd: true,
            },
        },
        {
            action: KeyAction.FormatQuote,
            keyCombo: {
                key: Key.GREATER_THAN,
                ctrlOrCmd: true,
                shiftKey: true,
            },
        },
        {
            action: KeyAction.EditUndo,
            keyCombo: {
                key: Key.Z,
                ctrlOrCmd: true,
            },
        },
        // Note: the following two bindings also work with just HOME and END, add them here?
        {
            action: KeyAction.MoveCursorToStart,
            keyCombo: {
                key: Key.HOME,
                ctrlOrCmd: true,
            },
        },
        {
            action: KeyAction.MoveCursorToEnd,
            keyCombo: {
                key: Key.END,
                ctrlOrCmd: true,
            },
        },
    ];
    if (isMac) {
        bindings.push({
            action: KeyAction.EditRedo,
            keyCombo: {
                key: Key.Z,
                ctrlOrCmd: true,
                shiftKey: true,
            },
        });
    } else {
        bindings.push({
            action: KeyAction.EditRedo,
            keyCombo: {
                key: Key.Y,
                ctrlOrCmd: true,
            },
        });
    }
    if (SettingsStore.getValue('MessageComposerInput.ctrlEnterToSend')) {
        bindings.push({
            action: KeyAction.Send,
            keyCombo: {
                key: Key.ENTER,
                ctrlOrCmd: true,
            },
        });
        bindings.push({
            action: KeyAction.NewLine,
            keyCombo: {
                key: Key.ENTER,
            },
        });
    } else {
        bindings.push({
            action: KeyAction.Send,
            keyCombo: {
                key: Key.ENTER,
            },
        });
        bindings.push({
            action: KeyAction.NewLine,
            keyCombo: {
                key: Key.ENTER,
                shiftKey: true,
            },
        });
        if (isMac) {
            bindings.push({
                action: KeyAction.NewLine,
                keyCombo: {
                    key: Key.ENTER,
                    altKey: true,
                },
            });
        }
    }
    return bindings;
}

const autocompleteBindings = (): KeyBinding[] => {
    return [
        {
            action: KeyAction.AutocompleteApply,
            keyCombo: {
                key: Key.TAB,
            },
        },
        {
            action: KeyAction.AutocompleteApply,
            keyCombo: {
                key: Key.TAB,
                ctrlKey: true,
            },
        },
        {
            action: KeyAction.AutocompleteApply,
            keyCombo: {
                key: Key.TAB,
                shiftKey: true,
            },
        },
        {
            action: KeyAction.AutocompleteCancel,
            keyCombo: {
                key: Key.ESCAPE,
            },
        },
        {
            action: KeyAction.AutocompletePrevSelection,
            keyCombo: {
                key: Key.ARROW_UP,
            },
        },
        {
            action: KeyAction.AutocompleteNextSelection,
            keyCombo: {
                key: Key.ARROW_DOWN,
            },
        },
    ];
}

const roomListBindings = (): KeyBinding[] => {
    return [
        {
            action: KeyAction.RoomListClearSearch,
            keyCombo: {
                key: Key.ESCAPE,
            },
        },
        {
            action: KeyAction.RoomListPrevRoom,
            keyCombo: {
                key: Key.ARROW_UP,
            },
        },
        {
            action: KeyAction.RoomListNextRoom,
            keyCombo: {
                key: Key.ARROW_DOWN,
            },
        },
        {
            action: KeyAction.RoomListSelectRoom,
            keyCombo: {
                key: Key.ENTER,
            },
        },
        {
            action: KeyAction.RoomListCollapseSection,
            keyCombo: {
                key: Key.ARROW_LEFT,
            },
        },
        {
            action: KeyAction.RoomListExpandSection,
            keyCombo: {
                key: Key.ARROW_RIGHT,
            },
        },
    ];
}

const roomBindings = (): KeyBinding[] => {
    const bindings = [
        {
            action: KeyAction.RoomFocusRoomSearch,
            keyCombo: {
                key: Key.K,
                ctrlOrCmd: true,
            },
        },
        {
            action: KeyAction.RoomScrollUp,
            keyCombo: {
                key: Key.PAGE_UP,
            },
        },
        {
            action: KeyAction.RoomScrollDown,
            keyCombo: {
                key: Key.PAGE_DOWN,
            },
        },
        {
            action: KeyAction.RoomDismissReadMarker,
            keyCombo: {
                key: Key.ESCAPE,
            },
        },
        {
            action: KeyAction.RoomUploadFile,
            keyCombo: {
                key: Key.U,
                ctrlOrCmd: true,
                shiftKey: true,
            },
        },
        {
            action: KeyAction.RoomJumpToFirstMessage,
            keyCombo: {
                key: Key.HOME,
                ctrlKey: true,
            },
        },
        {
            action: KeyAction.RoomJumpToLatestMessage,
            keyCombo: {
                key: Key.END,
                ctrlKey: true,
            },
        },
    ];

    if (SettingsStore.getValue('ctrlFForSearch')) {
        bindings.push({
            action: KeyAction.RoomSearch,
            keyCombo: {
                key: Key.F,
                ctrlOrCmd: true,
            },
        });
    }

    return bindings;
}

const navigationBindings = (): KeyBinding[] => {
    return [
        {
            action: KeyAction.NavToggleRoomSidePanel,
            keyCombo: {
                key: Key.PERIOD,
                ctrlOrCmd: true,
            },
        },
        {
            action: KeyAction.NavToggleUserMenu,
            // Ideally this would be CTRL+P for "Profile", but that's
            // taken by the print dialog. CTRL+I for "Information"
            // was previously chosen but conflicted with italics in
            // composer, so CTRL+` it is
            keyCombo: {
                key: Key.BACKTICK,
                ctrlOrCmd: true,
            },
        },
        {
            action: KeyAction.NavToggleShortCutDialog,
            keyCombo: {
                key: Key.SLASH,
                ctrlOrCmd: true,
            },
        },
        {
            action: KeyAction.NavToggleShortCutDialog,
            keyCombo: {
                key: Key.SLASH,
                ctrlOrCmd: true,
                shiftKey: true,
            },
        },
        {
            action: KeyAction.NavGoToHome,
            keyCombo: {
                key: Key.H,
                ctrlOrCmd: true,
                altKey: true,
            },
        },

        {
            action: KeyAction.NavSelectPrevRoom,
            keyCombo: {
                key: Key.ARROW_UP,
                altKey: true,
            },
        },
        {
            action: KeyAction.NavSelectNextRoom,
            keyCombo: {
                key: Key.ARROW_DOWN,
                altKey: true,
            },
        },
        {
            action: KeyAction.NavSelectPrevUnreadRoom,
            keyCombo: {
                key: Key.ARROW_UP,
                altKey: true,
                shiftKey: true,
            },
        },
        {
            action: KeyAction.NavSelectNextUnreadRoom,
            keyCombo: {
                key: Key.ARROW_DOWN,
                altKey: true,
                shiftKey: true,
            },
        },
    ]
}

/**
 * Helper method to check if a KeyboardEvent matches a KeyCombo
 *
 * Note, this method is only exported for testing.
 */
export function isKeyComboMatch(ev: KeyboardEvent | React.KeyboardEvent, combo: KeyCombo, onMac: boolean): boolean {
    if (combo.key !== undefined) {
        // When shift is pressed, letters are returned as upper case chars. In this case do a lower case comparison.
        // This works for letter combos such as shift + U as well for none letter combos such as shift + Escape.
        // If shift is not pressed, the toLowerCase conversion can be avoided.
        if (ev.shiftKey) {
            if (ev.key.toLowerCase() !== combo.key.toLowerCase()) {
                return false;
            }
        } else if (ev.key !== combo.key) {
            return false;
        }
    }

    const comboCtrl = combo.ctrlKey ?? false;
    const comboAlt = combo.altKey ?? false;
    const comboShift = combo.shiftKey ?? false;
    const comboMeta = combo.metaKey ?? false;
    // When ctrlOrCmd is set, the keys need do evaluated differently on PC and Mac
    if (combo.ctrlOrCmd) {
        if (onMac) {
            if (!ev.metaKey
                || ev.ctrlKey !== comboCtrl
                || ev.altKey !== comboAlt
                || ev.shiftKey !== comboShift) {
                return false;
            }
        } else {
            if (!ev.ctrlKey
                || ev.metaKey !== comboMeta
                || ev.altKey !== comboAlt
                || ev.shiftKey !== comboShift) {
                return false;
            }
        }
        return true;
    }

    if (ev.metaKey !== comboMeta
        || ev.ctrlKey !== comboCtrl
        || ev.altKey !== comboAlt
        || ev.shiftKey !== comboShift) {
        return false;
    }

    return true;
}

export type KeyBindingsGetter = () => KeyBinding[];

export class KeyBindingsManager {
    /**
     * Map of KeyBindingContext to a KeyBinding getter arrow function.
     *
     * Returning a getter function allowed to have dynamic bindings, e.g. when settings change the bindings can be
     * recalculated.
     */
    contextBindings: Record<KeyBindingContext, KeyBindingsGetter> = {
        [KeyBindingContext.MessageComposer]: messageComposerBindings,
        [KeyBindingContext.AutoComplete]: autocompleteBindings,
        [KeyBindingContext.RoomList]: roomListBindings,
        [KeyBindingContext.Room]: roomBindings,
        [KeyBindingContext.Navigation]: navigationBindings,
    };

    /**
     * Finds a matching KeyAction for a given KeyboardEvent
     */
    getAction(context: KeyBindingContext, ev: KeyboardEvent | React.KeyboardEvent): KeyAction {
        const bindings = this.contextBindings[context]?.();
        if (!bindings) {
            return KeyAction.None;
        }
        const binding = bindings.find(it => isKeyComboMatch(ev, it.keyCombo, isMac));
        if (binding) {
            return binding.action;
        }

        return KeyAction.None;
    }
}

const manager = new KeyBindingsManager();

export function getKeyBindingsManager(): KeyBindingsManager {
    return manager;
}