'use strict';

const FormData = require('form-data');
const { requestStream } = require('./http-client');

function collaboraBase(config) {
    return (config.collaboraUrl || '').replace(/\/$/, '');
}

function tlsOptions(config) {
    return config.verifyTls !== false && config.verifyTls !== 'false';
}

function buildMultipart(fields) {
    const form = new FormData();
    for (const field of fields) {
        if (field.buffer) {
            form.append(field.name, field.buffer, {
                filename: field.filename || 'document.bin',
                contentType: field.contentType || 'application/octet-stream'
            });
        } else if (field.value !== undefined) {
            form.append(field.name, String(field.value));
        }
    }
    return form;
}

async function postMultipart(config, endpoint, fields) {
    const form = buildMultipart(fields);
    const url = `${collaboraBase(config)}${endpoint}`;

    const res = await requestStream(
        {
            url,
            method: 'POST',
            headers: form.getHeaders(),
            rejectUnauthorized: tlsOptions(config)
        },
        (req) => form.pipe(req)
    );

    if (res.statusCode < 200 || res.statusCode >= 300) {
        const snippet = res.body.toString('utf8').slice(0, 300);
        throw new Error(`Collabora ${endpoint} misslyckades (${res.statusCode}): ${snippet}`);
    }

    if (!res.body || res.body.length === 0) {
        throw new Error(`Collabora ${endpoint} returnerade tomt svar — kontrollera intern URL och post_allow`);
    }

    return {
        buffer: res.body,
        contentType: res.headers['content-type'],
        statusCode: res.statusCode
    };
}

async function convertTo(config, { buffer, filename, format, extraFields = [] }) {
    const fmt = String(format || 'pdf').toLowerCase();
    const fields = [
        { name: 'data', buffer, filename: filename || 'document.bin' },
        ...extraFields
    ];

    try {
        return await postMultipart(config, `/cool/convert-to/${fmt}`, fields);
    } catch (err) {
        fields.push({ name: 'format', value: fmt });
        return postMultipart(config, '/cool/convert-to', fields);
    }
}

async function extractStructure(config, { buffer, filename, filter }) {
    const fields = [{ name: 'data', buffer, filename: filename || 'document.bin' }];
    if (filter) {
        fields.push({ name: 'filter', value: typeof filter === 'string' ? filter : JSON.stringify(filter) });
    }
    const res = await postMultipart(config, '/cool/extract-document-structure', fields);
    try {
        return JSON.parse(res.buffer.toString('utf8'));
    } catch {
        return { raw: res.buffer.toString('utf8') };
    }
}

async function transformStructure(config, { buffer, filename, transform }) {
    const fields = [
        { name: 'data', buffer, filename: filename || 'document.bin' },
        { name: 'transform', value: typeof transform === 'string' ? transform : JSON.stringify(transform) }
    ];
    const res = await postMultipart(config, '/cool/transform-document-structure', fields);
    return {
        buffer: res.buffer,
        contentType: res.contentType
    };
}

async function getCapabilities(config) {
    const url = `${collaboraBase(config)}/hosting/capabilities`;
    const { requestBuffer } = require('./http-client');
    const res = await requestBuffer({
        url,
        method: 'GET',
        rejectUnauthorized: tlsOptions(config)
    });
    if (res.statusCode < 200 || res.statusCode >= 300) {
        throw new Error(`Capabilities misslyckades (${res.statusCode})`);
    }
    return JSON.parse(res.body.toString('utf8'));
}

async function getDiscovery(config) {
    const url = `${collaboraBase(config)}/hosting/discovery`;
    const { requestBuffer } = require('./http-client');
    const res = await requestBuffer({
        url,
        method: 'GET',
        rejectUnauthorized: tlsOptions(config)
    });
    if (res.statusCode < 200 || res.statusCode >= 300) {
        throw new Error(`Discovery misslyckades (${res.statusCode})`);
    }
    return res.body.toString('utf8');
}

module.exports = {
    convertTo,
    extractStructure,
    transformStructure,
    getCapabilities,
    getDiscovery,
    postMultipart
};