pathwise.js

var assert = require('assert');
var defaults = require('levelup-defaults');
var bytewise = require('bytewise');
var type = require('component-type');
var after = require('after');
var streamToArray = require('stream-to-array');
const stringify = require('json-stable-stringify');
var { block } = require('./index')
module.exports = Pathwise;

function Pathwise(db) {
    assert(db, 'db required');
    this._db = defaults(db, {
        keyEncoding: bytewise,
        valueEncoding: 'json'
    });
}

Pathwise.prototype.put = function(path, obj, opts, fn) {
    if (typeof opts == 'function') {
        fn = opts;
        opts = {};
    }
    var batch = opts.batch || this._db.batch();
    this._write(batch, path, obj, fn);
    if (opts.batch) setImmediate(fn);
    else batch.write(fn);
};

Pathwise.prototype._write = function(batch, key, obj, fn) {
    var self = this;
    switch (type(obj)) {
        case 'object':
            var keys = Object.keys(obj);
            var next = after(keys.length, fn);
            keys.forEach(function(k) {
                self._write(batch, key.concat(k), obj[k], next);
            });
            break;
        case 'array':
            this._write(batch, key, arrToObj(obj), fn);
            break;
        default:
            batch.put(bytewise.encode(key), stringify(obj));
            break;
    }
}

Pathwise.prototype.batch = function(ops, pc) { // promise chain[resolve(), reject(), info]
    var self = this;
    var batch = this._db.batch();
    var next = after(ops.length, function(err) {
        if (err && pc[1]) {
            console.log('fail', err)
            pc[1](err)
        } else if (pc.length > 2) {
            block.ops.push('W')
            batch.write(()=>{pc[0](pc[2])})
        } else {
            block.ops.push('W')
            batch.write(()=>{pc[0]()})
        }
    });
    ops.forEach(function(op) {
        block.ops.push(stringify({type: op.type, path: op.path, data: op.data}))
        if (op.type == 'put') self.put(op.path, op.data, { batch: batch }, next)
        else if (op.type == 'del') self.del(op.path, { batch: batch }, next);
    });
};

Pathwise.prototype.get = function(path, fn) {
    var ret = {};
    var el = ret;

    streamToArray(this._db.createReadStream({
        start: path,
        end: path.concat(undefined)
    }), function(err, data) {
        if (err) return fn(err);
        let er = null
        try {
            data.forEach(function(kv) {
                var segs = kv.key.slice(path.length);
                if (segs.length) {
                    segs.forEach(function(seg, idx) {
                        if (!el[seg]) {
                            if (idx == segs.length - 1) {
                                el[seg] = kv.value;
                            } else {
                                el[seg] = {};
                            }
                        }
                        el = el[seg];
                    });
                    el = ret;
                } else {
                    ret = kv.value;
                }
            });
        } catch (err) { er = err }
        fn(er, ret);
    });
};

Pathwise.prototype.getWith = function(path, obj, fn) {
    var ret = {};
    var el = ret;

    streamToArray(this._db.createReadStream({
        start: path,
        end: path.concat(undefined)
    }), function(err, data) {
        if (err) return fn(err);
        let er = null
        try {
            data.forEach(function(kv) {
                var segs = kv.key.slice(path.length);
                if (segs.length) {
                    segs.forEach(function(seg, idx) {
                        if (!el[seg]) {
                            if (idx == segs.length - 1) {
                                el[seg] = kv.value;
                            } else {
                                el[seg] = {};
                            }
                        }
                        el = el[seg];
                    });
                    el = ret;
                } else {
                    ret = kv.value;
                }
            });
        } catch (err) { er = err }
        fn(er, ret, obj);
    });
};

Pathwise.prototype.del = function(path, opts, fn) {
    if (typeof opts == 'function') {
        fn = opts;
        opts = {};
    }
    var batch = opts.batch || this._db.batch();

    streamToArray(this._db.createKeyStream({
        start: path,
        end: path.concat(undefined)
    }), function(err, keys) {
        if (err) return fn(err);
        keys.forEach(function(key) { batch.del(bytewise.encode(key)) });
        if (opts.batch) fn();
        else batch.write(fn);
    });
};

Pathwise.prototype.children = function(path, fn) {
    streamToArray(this._db.createReadStream({
        start: path,
        end: path.concat(undefined)
    }), function(err, kv) {
        if (err) return fn(err);
        fn(null, kv.map(function(_kv) {
            return _kv.key[path.length] || _kv.value;
        }));
    });
}

Pathwise.prototype.someChildren = function(path, opts, fn) {
    streamToArray(this._db.createReadStream({
        start: [...path, opts.gte],
        end: [...path, opts.lte].concat(undefined)
    }), function(err, kv) {
        if (err) return fn(err);
        fn(null, kv.map(function(_kv) {
            return _kv.key[path.length] || _kv.value;
        }));
    });
}

function arrToObj(arr) {
    var obj = {};
    arr.forEach(function(el, idx) {
        obj[idx] = el;
    });
    return obj;
}