/**
 * @node nextcloud-talk
 * @name Nextcloud Talk
 * @category integration
 * @version 1.0.0
 * @description Post a message to a Nextcloud Talk conversation, or read the recent messages in one
 * @icon message-square
 */

const configSchema = {
    type: 'object',
    properties: {
        baseUrl: {
            type: 'string',
            title: 'Nextcloud URL',
            description: 'Address of the Nextcloud instance, e.g. https://cloud.example.com'
        },
        credentialId: {
            type: 'string',
            title: 'Credential',
            description: 'A basic credential holding the username and an app password. Not needed for a bot webhook.',
            dynamicOptions: {
                source: 'credentials',
                filter: { type: 'basic' }
            }
        },
        action: {
            type: 'string',
            title: 'Action',
            enum: ['send', 'read'],
            default: 'send',
            description: 'Post a message, or read the recent ones'
        },
        token: {
            type: 'string',
            title: 'Conversation Token',
            description: 'The token in the conversation URL, e.g. the a1b2c3d4 in /call/a1b2c3d4'
        },
        message: {
            type: 'string',
            title: 'Message',
            description: 'What to post. Supports {{variable}} interpolation.'
        },
        replyTo: {
            type: 'string',
            title: 'Reply To',
            description: 'Post as a reply to this message id'
        },
        silent: {
            type: 'boolean',
            title: 'Send Silently',
            description: 'Post without notifying participants',
            default: false
        },
        limit: {
            type: 'integer',
            title: 'Limit',
            description: 'How many messages to read',
            default: 20,
            minimum: 1,
            maximum: 200
        },
        timeoutMs: {
            type: 'number',
            title: 'Timeout (ms)',
            default: 30000
        }
    },
    required: ['baseUrl', 'credentialId', 'token']
};

const inputSchema = {
    type: 'object',
    properties: {
        token: { type: 'string', description: 'Overrides the configured conversation' },
        message: { type: 'string', description: 'Overrides the configured message' }
    }
};

const outputSchema = {
    type: 'object',
    properties: {
        success: { type: 'boolean' },
        messageId: { type: 'integer', description: 'The id Talk gave the posted message' },
        token: { type: 'string', description: 'The conversation it was posted to' },
        messages: {
            type: 'array',
            description: 'Recent messages, when reading',
            items: {
                type: 'object',
                properties: {
                    id: { type: 'integer' },
                    actorId: { type: 'string' },
                    actorDisplayName: { type: 'string' },
                    message: { type: 'string' },
                    timestamp: { type: 'integer' }
                }
            }
        },
        count: { type: 'integer', description: 'How many messages were read' }
    }
};

const outputs = [
    { name: 'main', displayName: 'Result', type: 'object', color: '#3b82f6' }
];

// A connection hands the previous node's whole output over as input.data, and
// some nodes wrap their own return in a result object on top of that. Rather
// than guess which shape arrived, the layers are flattened with the innermost
// winning, so a field set anywhere in the chain is found.
function incoming(input) {
    const isPlain = (v) => v && typeof v === 'object' && !Array.isArray(v);
    const merged = {};

    for (const layer of [input, input && input.data, input && input.data && input.data.result]) {
        if (!isPlain(layer)) continue;
        for (const key of Object.keys(layer)) {
            merged[key] = layer[key];
        }
    }

    return merged;
}

// Talk is reached through the OCS API, which refuses any request that does not
// declare itself as an API call with this header, and returns XML unless asked
// for JSON.
function ocsHeaders(credential) {
    const headers = {
        'OCS-APIRequest': 'true',
        'Accept': 'application/json',
        'Content-Type': 'application/json'
    };
    if (credential && credential.headerName) {
        headers[credential.headerName] = credential.headerValue;
    }
    return headers;
}

function readCredential(credentialId) {
    const credential = smartbotic.credentials.get(credentialId);
    if (!credential || !credential.success) {
        throw new Error('Could not read the Nextcloud credential: ' +
            ((credential && credential.error) || 'unknown error'));
    }
    return credential;
}

// A Nextcloud that is unhappy answers with XML, or with the HTML of a login
// page, and parsing that as JSON throws a bare syntax error that says nothing
// about which request failed. The body is reported instead.
function parseJsonResponse(response, what) {
    if (typeof response.data !== 'string') {
        return response.data;
    }

    try {
        return JSON.parse(response.data);
    } catch (e) {
        const snippet = response.data.substring(0, 200).replace(/\s+/g, ' ');
        throw new Error('Nextcloud Talk ' + what + ' failed: HTTP ' + response.status +
            ' returned ' + (response.headers && response.headers['content-type'] || 'an unreadable body') +
            ' instead of JSON: ' + snippet);
    }
}

// OCS wraps everything in ocs.meta plus ocs.data, and reports failure in the
// meta rather than always in the status code.
function unwrapOcs(response, what) {
    const body = parseJsonResponse(response, what);
    const ocs = body && body.ocs;

    if (!ocs) {
        throw new Error('Nextcloud Talk ' + what + ' failed: HTTP ' + response.status +
            ' returned no OCS envelope: ' + JSON.stringify(body).substring(0, 200));
    }

    const status = ocs.meta && ocs.meta.statuscode;
    if (status && (status < 200 || status >= 300)) {
        throw new Error('Nextcloud Talk ' + what + ' failed: ' +
            ((ocs.meta && ocs.meta.message) || ('OCS ' + status)));
    }

    return ocs.data;
}

module.exports = {
    configSchema,
    inputSchema,
    outputSchema,
    outputs,

    async execute(config, input, context) {
        const from = incoming(input);

        const base = String(config.baseUrl || '').replace(/\/+$/, '');
        if (!base) {
            throw new Error('The Nextcloud URL is required');
        }

        const token = String(from.token || config.token || '').trim();
        if (!token) {
            throw new Error('A conversation token is required');
        }

        const credential = readCredential(config.credentialId);
        const headers = ocsHeaders(credential);
        const timeout = Number(config.timeoutMs) || 30000;
        const chatUrl = base + '/ocs/v2.php/apps/spreed/api/v1/chat/' + token;

        if ((config.action || 'send') === 'read') {
            const limit = Number(config.limit) || 20;

            // lookIntoFuture=0 asks for the messages already there rather than
            // holding the connection open waiting for the next one.
            const response = smartbotic.http.request({
                method: 'GET',
                url: chatUrl + '?format=json&lookIntoFuture=0&limit=' + limit,
                headers: headers,
                timeout: timeout
            });

            const data = unwrapOcs(response, 'read') || [];
            const messages = data.map(function (entry) {
                return {
                    id: entry.id,
                    actorId: entry.actorId,
                    actorDisplayName: entry.actorDisplayName,
                    message: entry.message,
                    timestamp: entry.timestamp
                };
            });

            return {
                success: true,
                token: token,
                messages: messages,
                count: messages.length
            };
        }

        const message = from.message || config.message || '';
        if (!message) {
            throw new Error('A message is required');
        }

        const payload = { message: message };
        if (config.replyTo) {
            payload.replyTo = Number(config.replyTo);
        }
        if (config.silent === true) {
            payload.silent = true;
        }

        const response = smartbotic.http.request({
            method: 'POST',
            url: chatUrl + '?format=json',
            headers: headers,
            body: JSON.stringify(payload),
            timeout: timeout
        });

        const data = unwrapOcs(response, 'send') || {};
        smartbotic.log.info('Nextcloud Talk: posted to conversation ' + token);

        return {
            success: true,
            messageId: data.id,
            token: token
        };
    }
};