/*
Copyright 2017 Vector Creations Ltd
Copyright 2022 The Matrix.org Foundation C.I.C.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

import React, { createRef } from "react";
import { MatrixClient } from "matrix-js-sdk/src/matrix";
import { logger } from "matrix-js-sdk/src/logger";

import * as MegolmExportEncryption from "../../../../utils/MegolmExportEncryption";
import { _t } from "../../../../languageHandler";
import BaseDialog from "../../../../components/views/dialogs/BaseDialog";
import Field from "../../../../components/views/elements/Field";

function readFileAsArrayBuffer(file: File): Promise<ArrayBuffer> {
    return new Promise((resolve, reject) => {
        const reader = new FileReader();
        reader.onload = (e) => {
            if (e.target?.result) {
                resolve(e.target.result as ArrayBuffer);
            } else {
                reject(new Error("Failed to read file due to unknown error"));
            }
        };
        reader.onerror = reject;

        reader.readAsArrayBuffer(file);
    });
}

enum Phase {
    Edit = "edit",
    Importing = "importing",
}

interface IProps {
    matrixClient: MatrixClient;
    onFinished(imported?: boolean): void;
}

interface IState {
    enableSubmit: boolean;
    phase: Phase;
    errStr: string | null;
    passphrase: string;
}

export default class ImportE2eKeysDialog extends React.Component<IProps, IState> {
    private unmounted = false;
    private file = createRef<HTMLInputElement>();

    public constructor(props: IProps) {
        super(props);

        this.state = {
            enableSubmit: false,
            phase: Phase.Edit,
            errStr: null,
            passphrase: "",
        };
    }

    public componentWillUnmount(): void {
        this.unmounted = true;
    }

    private onFormChange = (): void => {
        const files = this.file.current?.files;
        this.setState({
            enableSubmit: this.state.passphrase !== "" && !!files?.length,
        });
    };

    private onPassphraseChange = (ev: React.ChangeEvent<HTMLInputElement>): void => {
        this.setState({ passphrase: ev.target.value }, this.onFormChange); // update general form state too
    };

    private onFormSubmit = (ev: React.FormEvent): boolean => {
        ev.preventDefault();
        // noinspection JSIgnoredPromiseFromCall
        const file = this.file.current?.files?.[0];
        if (file) {
            this.startImport(file, this.state.passphrase);
        }
        return false;
    };

    private startImport(file: File, passphrase: string): Promise<void> {
        this.setState({
            errStr: null,
            phase: Phase.Importing,
        });

        return readFileAsArrayBuffer(file)
            .then((arrayBuffer) => {
                return MegolmExportEncryption.decryptMegolmKeyFile(arrayBuffer, passphrase);
            })
            .then((keys) => {
                return this.props.matrixClient.importRoomKeys(JSON.parse(keys));
            })
            .then(() => {
                // TODO: it would probably be nice to give some feedback about what we've imported here.
                this.props.onFinished(true);
            })
            .catch((e) => {
                logger.error("Error importing e2e keys:", e);
                if (this.unmounted) {
                    return;
                }
                const msg = e.friendlyText || _t("error|unknown");
                this.setState({
                    errStr: msg,
                    phase: Phase.Edit,
                });
            });
    }

    private onCancelClick = (ev: React.MouseEvent): boolean => {
        ev.preventDefault();
        this.props.onFinished(false);
        return false;
    };

    public render(): React.ReactNode {
        const disableForm = this.state.phase !== Phase.Edit;

        return (
            <BaseDialog
                className="mx_importE2eKeysDialog"
                onFinished={this.props.onFinished}
                title={_t("settings|key_export_import|import_title")}
            >
                <form onSubmit={this.onFormSubmit}>
                    <div className="mx_Dialog_content">
                        <p>{_t("settings|key_export_import|import_description_1")}</p>
                        <p>{_t("settings|key_export_import|import_description_2")}</p>
                        <div className="error">{this.state.errStr}</div>
                        <div className="mx_E2eKeysDialog_inputTable">
                            <div className="mx_E2eKeysDialog_inputRow">
                                <div className="mx_E2eKeysDialog_inputLabel">
                                    <label htmlFor="importFile">
                                        {_t("settings|key_export_import|file_to_import")}
                                    </label>
                                </div>
                                <div className="mx_E2eKeysDialog_inputCell">
                                    <input
                                        ref={this.file}
                                        id="importFile"
                                        type="file"
                                        autoFocus={true}
                                        onChange={this.onFormChange}
                                        disabled={disableForm}
                                    />
                                </div>
                            </div>
                            <div className="mx_E2eKeysDialog_inputRow">
                                <Field
                                    label={_t("settings|key_export_import|enter_passphrase")}
                                    value={this.state.passphrase}
                                    onChange={this.onPassphraseChange}
                                    size={64}
                                    type="password"
                                    disabled={disableForm}
                                />
                            </div>
                        </div>
                    </div>
                    <div className="mx_Dialog_buttons">
                        <input
                            className="mx_Dialog_primary"
                            type="submit"
                            value={_t("action|import")}
                            disabled={!this.state.enableSubmit || disableForm}
                        />
                        <button onClick={this.onCancelClick} disabled={disableForm}>
                            {_t("action|cancel")}
                        </button>
                    </div>
                </form>
            </BaseDialog>
        );
    }
}