// Copyright BigchainDB GmbH and BigchainDB contributors
// SPDX-License-Identifier: (Apache-2.0 AND CC-BY-4.0)
// Code is Apache-2.0 and docs are CC-BY-4.0

import { sprintf } from 'sprintf-js'

// Regexes taken from or inspired by sprintf-js
const Regex = {
    TEMPLATE_LITERAL: /\${([^)]+?)}/g,
    KEY: /^([a-z_][a-z_\d]*)/i,
    KEY_ACCESS: /^\.([a-z_][a-z_\d]*)/i,
    INDEX_ACCESS: /^\[(\d+)\]/
}

/**
 * imported from https://github.com/bigchaindb/js-utility-belt/
 * @private
 * Formats strings similarly to C's sprintf, with the addition of '${...}' formats.
 *
 * Makes a first pass replacing '${...}' formats before passing the expanded string and other
 * arguments to sprintf-js. For more information on what sprintf can do, see
 * https://github.com/alexei/sprintf.js.
 *
 * Examples:
 *   formatText('Hi there ${dimi}!', { dimi: 'Dimi' })
 *       => 'Hi there Dimi!'
 *
 *   formatText('${database} is %(status)s', { database: 'BigchainDB', status: 'big' })
 *       => 'BigchainDB is big'
 *
 * Like sprintf-js, string interpolation for keywords and indexes is supported too:
 *   formatText('Berlin is best known for its ${berlin.topKnownFor[0].name}', {
 *       berlin: {
 *           topKnownFor: [{
 *               name: 'Currywurst'
 *           }, ...
 *           ]
 *       }
 *   })
 *       => 'Berlin is best known for its Currywurst'
 */
export default function formatText(s, ...argv) {
    let expandedFormatStr = s

    // Try to replace formats of the form '${...}' if named replacement fields are used
    if (s && argv.length === 1 && typeof argv[0] === 'object') {
        const templateSpecObj = argv[0]

        expandedFormatStr = s.replace(Regex.TEMPLATE_LITERAL, (match, replacement) => {
            let interpolationLeft = replacement

            /**
             * @private
             * Interpolation algorithm inspired by sprintf-js.
             *
             * Goes through the replacement string getting the left-most key or index to interpolate
             * on each pass. `value` at each step holds the last interpolation result, `curMatch` is
             * the current property match, and `interpolationLeft` is the portion of the replacement
             * string still to be interpolated.
             *
             * It's useful to note that RegExp.exec() returns with an array holding:
             *   [0]:  Full string matched
             *   [1+]: Matching groups
             *
             * And that in the regexes defined, the first matching group always corresponds to the
             * property matched.
             */
            let value
            let curMatch = Regex.KEY.exec(interpolationLeft)
            if (curMatch !== null) {
                value = templateSpecObj[curMatch[1]]

                // Assigning in the conditionals here makes the code less bloated
                /* eslint-disable no-cond-assign */
                while ((interpolationLeft = interpolationLeft.substring(curMatch[0].length)) &&
                    value != null) {
                    if ((curMatch = Regex.KEY_ACCESS.exec(interpolationLeft))) {
                        value = value[curMatch[1]]
                    } else if ((curMatch = Regex.INDEX_ACCESS.exec(interpolationLeft))) {
                        value = value[curMatch[1]]
                    } else {
                        break
                    }
                }
                /* eslint-enable no-cond-assign */
            }

            // If there's anything left to interpolate by the end then we've failed to interpolate
            // the entire replacement string.
            if (interpolationLeft.length) {
                throw new SyntaxError(`[formatText] failed to parse named argument key: ${replacement}`)
            }

            return value
        })
    }

    return sprintf(expandedFormatStr, ...argv)
}