/**
 * @node bluesky
 * @name Bluesky
 * @category integration
 * @version 1.0.0
 * @description Post to Bluesky over the AT Protocol, with links, tags and mentions made clickable
 * @icon at-sign
 */

const configSchema = {
    type: 'object',
    properties: {
        credentialId: {
            type: 'string',
            title: 'Account Credential',
            description: 'A basic credential whose username is the handle, such as name.bsky.social, and whose password is an app password created under Settings, App Passwords. Never your account password',
            dynamicOptions: {
                source: 'credentials',
                filter: { type: ['basic'] }
            }
        },
        service: {
            type: 'string',
            title: 'Service',
            description: 'Address of the PDS holding the account. Only change this for a self-hosted server',
            default: 'https://bsky.social'
        },
        operation: {
            type: 'string',
            title: 'Operation',
            enum: ['post', 'delete'],
            default: 'post',
            description: 'post publishes a new entry, delete removes one this account owns'
        },
        text: {
            type: 'string',
            title: 'Text',
            description: 'The post body, up to 300 graphemes. Supports {{variable}} interpolation',
            format: 'textarea'
        },
        detectFacets: {
            type: 'boolean',
            title: 'Detect Links, Tags and Mentions',
            description: 'Find URLs, #hashtags and @handles in the text and mark them up so Bluesky renders them as links. Each mention costs one extra request to resolve the handle',
            default: true
        },
        languages: {
            type: 'string',
            title: 'Languages',
            description: 'Comma separated language codes for the post, such as en or en,hu. Leave empty to send none',
            default: 'en'
        },
        replyTo: {
            type: 'string',
            title: 'Reply To',
            description: 'An at:// URI of a post to reply to. The node looks up its thread root itself'
        },
        images: {
            type: 'array',
            title: 'Images',
            description: 'Up to four images to attach. Each is uploaded from the file store before the post is created',
            items: {
                type: 'object',
                properties: {
                    fileId: {
                        type: 'string',
                        title: 'Stored File ID',
                        description: 'Id of the image in the file store'
                    },
                    alt: {
                        type: 'string',
                        title: 'Alt Text',
                        description: 'Description of the image for people using a screen reader. Bluesky shows an ALT badge when this is set'
                    }
                }
            }
        },
        uri: {
            type: 'string',
            title: 'Post URI',
            description: 'The at:// URI of the post to remove, for the delete operation'
        },
        timeout: {
            type: 'number',
            title: 'Timeout (ms)',
            default: 30000
        }
    },
    required: ['credentialId']
};

const inputSchema = {
    type: 'object',
    properties: {
        data: { type: 'any' }
    }
};

const outputSchema = {
    type: 'object',
    properties: {
        uri: { type: 'string', description: 'at:// URI of the post that was created or removed' },
        cid: { type: 'string', description: 'Content id of the created post' },
        url: { type: 'string', description: 'Browsable https://bsky.app address of the created post' },
        handle: { type: 'string', description: 'Handle the post was made as' },
        did: { type: 'string', description: 'DID of the posting account' },
        imageCount: { type: 'number', description: 'How many images were attached' }
    }
};

// Facet ranges are UTF-8 byte offsets, while JavaScript indexes UTF-16 code
// units. Any emoji or accented character ahead of a link shifts the two apart,
// and a facet built from string indexes then highlights the wrong span.
function utf8Length(text) {
    let bytes = 0;
    for (let i = 0; i < text.length; i++) {
        const code = text.charCodeAt(i);
        if (code < 0x80) {
            bytes += 1;
        } else if (code < 0x800) {
            bytes += 2;
        } else if (code >= 0xd800 && code <= 0xdbff) {
            bytes += 4;
            i++;
        } else {
            bytes += 3;
        }
    }
    return bytes;
}

function byteRange(text, start, length) {
    const byteStart = utf8Length(text.substring(0, start));
    return {
        byteStart: byteStart,
        byteEnd: byteStart + utf8Length(text.substring(start, start + length))
    };
}

function readCredential(credentialId) {
    const auth = smartbotic.credentials.get(credentialId);
    if (!auth || auth.success !== true) {
        throw new Error('Bluesky: could not read the account credential: ' +
            ((auth && auth.error) || 'unknown error'));
    }

    const value = auth.headerValue || '';
    if (value.indexOf('Basic ') !== 0) {
        throw new Error('Bluesky: the credential must be a basic one, holding the handle as ' +
            'its username and an app password as its password');
    }

    const decoded = smartbotic.utils.base64Decode(value.substring(6));
    const separator = decoded.indexOf(':');
    if (separator < 1) {
        throw new Error('Bluesky: the credential is malformed, expected a username and a password');
    }

    const identifier = decoded.substring(0, separator);
    const password = decoded.substring(separator + 1);
    if (!identifier || !password) {
        throw new Error('Bluesky: the credential needs both a handle and an app password');
    }

    return { identifier: identifier, password: password };
}

function call(options) {
    const response = smartbotic.http.request(options);

    let body = response.data;
    if (typeof body === 'string' && body.length > 0) {
        try {
            body = JSON.parse(body);
        } catch (e) {
            const snippet = body.substring(0, 200).replace(/\s+/g, ' ');
            throw new Error('Bluesky: ' + options.what + ' returned HTTP ' + response.status +
                ' with a body that is not JSON: ' + snippet);
        }
    }

    if (response.status < 200 || response.status >= 300) {
        const detail = (body && (body.message || body.error)) || ('HTTP ' + response.status);
        throw new Error('Bluesky: ' + options.what + ' failed: ' + detail);
    }

    return body || {};
}

function createSession(service, credential, timeout) {
    return call({
        method: 'POST',
        url: service + '/xrpc/com.atproto.server.createSession',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
            identifier: credential.identifier,
            password: credential.password
        }),
        timeout: timeout,
        what: 'sign in'
    });
}

// at://did:plc:xyz/app.bsky.feed.post/3k2a4b
function parseAtUri(uri, what) {
    const match = String(uri || '').match(/^at:\/\/([^/]+)\/([^/]+)\/([^/]+)$/);
    if (!match) {
        throw new Error('Bluesky: ' + what + ' must be an at:// URI like ' +
            'at://did:plc:example/app.bsky.feed.post/3k2a4b, got "' + uri + '"');
    }
    return { repo: match[1], collection: match[2], rkey: match[3] };
}

function findLinks(text) {
    const found = [];
    const pattern = /https?:\/\/[^\s]+/g;
    let match;
    while ((match = pattern.exec(text)) !== null) {
        // A URL that ends a sentence swallows the punctuation, and the shortened
        // link then 404s. Trailing characters that cannot end a real URL go back
        // to the sentence - but a closing bracket is only punctuation when it
        // has no opener inside the URL, or every Wikipedia link ending in
        // "_(disambiguation)" loses its last character.
        let value = match[0];
        while (value.length > 0) {
            const last = value.charAt(value.length - 1);
            if ('.,;:!?\'"'.indexOf(last) !== -1) {
                value = value.substring(0, value.length - 1);
                continue;
            }
            const opener = last === ')' ? '(' : last === ']' ? '[' : last === '}' ? '{' : '';
            if (opener !== '') {
                const opened = value.split(opener).length - 1;
                const closed = value.split(last).length - 1;
                if (closed > opened) {
                    value = value.substring(0, value.length - 1);
                    continue;
                }
            }
            break;
        }
        if (value.length === 0) {
            continue;
        }
        const range = byteRange(text, match.index, value.length);
        found.push({
            index: range,
            features: [{ $type: 'app.bsky.richtext.facet#link', uri: value }]
        });
    }
    return found;
}

function findTags(text) {
    const found = [];
    const pattern = /(^|\s)#([^\s#]+)/g;
    let match;
    while ((match = pattern.exec(text)) !== null) {
        const tag = match[2].replace(/[.,;:!?]+$/, '');
        if (tag.length === 0) {
            continue;
        }
        const start = match.index + match[1].length;
        const range = byteRange(text, start, tag.length + 1);
        found.push({
            index: range,
            features: [{ $type: 'app.bsky.richtext.facet#tag', tag: tag }]
        });
    }
    return found;
}

function findMentions(text, service, timeout) {
    const found = [];
    const pattern = /(^|\s)@([a-zA-Z0-9][a-zA-Z0-9-]*(?:\.[a-zA-Z0-9-]+)+)/g;
    let match;
    while ((match = pattern.exec(text)) !== null) {
        const handle = match[2].replace(/[.,;:!?]+$/, '');
        if (handle.indexOf('.') === -1) {
            continue;
        }

        let resolved;
        try {
            resolved = call({
                method: 'GET',
                url: service + '/xrpc/com.atproto.identity.resolveHandle?handle=' +
                    encodeURIComponent(handle),
                timeout: timeout,
                what: 'resolving @' + handle
            });
        } catch (e) {
            // An unknown handle is ordinary text, not a failure. Posting it as
            // plain text is what the author sees in the composer anyway.
            smartbotic.log.info('Bluesky: @' + handle + ' did not resolve, leaving it as text');
            continue;
        }

        if (!resolved || !resolved.did) {
            continue;
        }

        const start = match.index + match[1].length;
        const range = byteRange(text, start, handle.length + 1);
        found.push({
            index: range,
            features: [{ $type: 'app.bsky.richtext.facet#mention', did: resolved.did }]
        });
    }
    return found;
}

// Bluesky rejects anything over a megabyte on the blob upload, and the message
// it returns names a byte count rather than the picture, so the check happens
// here where the file is still identifiable.
const MAX_IMAGE_BYTES = 1000000;
const MAX_IMAGES = 4;

function uploadImages(service, token, images, timeout) {
    if (images.length > MAX_IMAGES) {
        throw new Error('Bluesky: a post takes at most ' + MAX_IMAGES + ' images, got ' + images.length);
    }

    const uploaded = [];

    for (const entry of images) {
        const fileId = entry && entry.fileId;
        if (!fileId) {
            throw new Error('Bluesky: an image entry has no stored file id');
        }

        const info = smartbotic.storage.getFileInfo(fileId);
        const file = smartbotic.storage.downloadFile(fileId);
        if (!file || file.success !== true || !file.data) {
            throw new Error('Bluesky: stored file ' + fileId + ' could not be read');
        }

        const mimeType = (info && info.mimeType) || 'image/jpeg';
        if (mimeType.indexOf('image/') !== 0) {
            throw new Error('Bluesky: stored file ' + fileId + ' is ' + mimeType +
                ', which is not an image');
        }

        // file.data is base64, so its decoded length is what the server sees.
        const padding = (file.data.match(/=+$/) || [''])[0].length;
        const size = Math.floor(file.data.length / 4) * 3 - padding;
        if (size > MAX_IMAGE_BYTES) {
            throw new Error('Bluesky: image ' + ((info && info.name) || fileId) + ' is ' +
                Math.round(size / 1024) + ' KB, over the ' +
                Math.round(MAX_IMAGE_BYTES / 1024) + ' KB limit. Resize it before posting');
        }

        const blob = call({
            method: 'POST',
            url: service + '/xrpc/com.atproto.repo.uploadBlob',
            headers: {
                'Authorization': 'Bearer ' + token,
                'Content-Type': mimeType
            },
            bodyBase64: file.data,
            timeout: timeout,
            what: 'uploading ' + ((info && info.name) || fileId)
        });

        if (!blob || !blob.blob) {
            throw new Error('Bluesky: the upload of ' + ((info && info.name) || fileId) +
                ' returned no blob reference');
        }

        uploaded.push({
            alt: (entry && entry.alt) || '',
            image: blob.blob
        });
    }

    return uploaded;
}

function buildReply(service, token, replyTo, timeout) {
    const parent = parseAtUri(replyTo, 'Reply To');
    const record = call({
        method: 'GET',
        url: service + '/xrpc/com.atproto.repo.getRecord?repo=' + encodeURIComponent(parent.repo) +
            '&collection=' + encodeURIComponent(parent.collection) +
            '&rkey=' + encodeURIComponent(parent.rkey),
        headers: { 'Authorization': 'Bearer ' + token },
        timeout: timeout,
        what: 'reading the post being replied to'
    });

    if (!record.uri || !record.cid) {
        throw new Error('Bluesky: the post at ' + replyTo + ' could not be read');
    }

    const parentRef = { uri: record.uri, cid: record.cid };

    // Replying to a reply must point at the thread root, not at the post being
    // answered, or the reply hangs outside the thread.
    const existingRoot = record.value && record.value.reply && record.value.reply.root;
    const root = existingRoot && existingRoot.uri && existingRoot.cid
        ? { uri: existingRoot.uri, cid: existingRoot.cid }
        : parentRef;

    return { root: root, parent: parentRef };
}

async function execute(config, input, context) {
    const operation = config.operation || 'post';
    const service = (config.service || 'https://bsky.social').replace(/\/+$/, '');
    const timeout = Number(config.timeout) || 30000;

    if (!config.credentialId) {
        throw new Error('Bluesky: an account credential is required');
    }

    const credential = readCredential(config.credentialId);
    const session = createSession(service, credential, timeout);

    if (!session.accessJwt || !session.did) {
        throw new Error('Bluesky: sign in returned no session for ' + credential.identifier);
    }

    const token = session.accessJwt;

    if (operation === 'delete') {
        const target = parseAtUri(config.uri, 'Post URI');
        if (target.repo !== session.did && target.repo !== session.handle) {
            throw new Error('Bluesky: ' + config.uri + ' does not belong to ' +
                session.handle + ', and only your own posts can be deleted');
        }

        call({
            method: 'POST',
            url: service + '/xrpc/com.atproto.repo.deleteRecord',
            headers: {
                'Authorization': 'Bearer ' + token,
                'Content-Type': 'application/json'
            },
            body: JSON.stringify({
                repo: session.did,
                collection: target.collection,
                rkey: target.rkey
            }),
            timeout: timeout,
            what: 'deleting the post'
        });

        smartbotic.log.info('Bluesky: deleted ' + config.uri);

        return {
            uri: config.uri,
            handle: session.handle,
            did: session.did
        };
    }

    const text = config.text;
    if (typeof text !== 'string' || text.length === 0) {
        throw new Error('Bluesky: post text is required');
    }

    const record = {
        $type: 'app.bsky.feed.post',
        text: text,
        createdAt: new Date().toISOString()
    };

    const languages = String(config.languages || '')
        .split(',')
        .map(function (code) { return code.trim(); })
        .filter(function (code) { return code.length > 0; });
    if (languages.length > 0) {
        record.langs = languages;
    }

    if (config.detectFacets !== false) {
        const facets = findLinks(text)
            .concat(findTags(text))
            .concat(findMentions(text, service, timeout));
        if (facets.length > 0) {
            facets.sort(function (left, right) {
                return left.index.byteStart - right.index.byteStart;
            });
            record.facets = facets;
        }
    }

    if (config.replyTo) {
        record.reply = buildReply(service, token, config.replyTo, timeout);
    }

    const images = Array.isArray(config.images) ? config.images : [];
    if (images.length > 0) {
        record.embed = {
            $type: 'app.bsky.embed.images',
            images: uploadImages(service, token, images, timeout)
        };
    }

    const created = call({
        method: 'POST',
        url: service + '/xrpc/com.atproto.repo.createRecord',
        headers: {
            'Authorization': 'Bearer ' + token,
            'Content-Type': 'application/json'
        },
        body: JSON.stringify({
            repo: session.did,
            collection: 'app.bsky.feed.post',
            record: record
        }),
        timeout: timeout,
        what: 'creating the post'
    });

    if (!created.uri) {
        throw new Error('Bluesky: the post was accepted but no URI came back');
    }

    const rkey = created.uri.substring(created.uri.lastIndexOf('/') + 1);
    const facetCount = record.facets ? record.facets.length : 0;
    const imageCount = record.embed ? record.embed.images.length : 0;
    smartbotic.log.info('Bluesky: posted as ' + session.handle + ' with ' + facetCount +
        ' facets and ' + imageCount + ' images');

    return {
        uri: created.uri,
        cid: created.cid || '',
        url: 'https://bsky.app/profile/' + session.handle + '/post/' + rkey,
        handle: session.handle,
        did: session.did,
        imageCount: imageCount
    };
}

module.exports = { configSchema, inputSchema, outputSchema, execute };