'use strict';

/** @ignore */
const ENTRIES = 'ENTRIES';
/** @ignore */
const KEYS = 'KEYS';
/** @ignore */
const VALUES = 'VALUES';
/** @ignore */
const LEAF = '';
/**
 * @private
 */
class TreeIterator {
    constructor(set, type) {
        const node = set._tree;
        const keys = Array.from(node.keys());
        this.set = set;
        this._type = type;
        this._path = keys.length > 0 ? [{ node, keys }] : [];
    }
    next() {
        const value = this.dive();
        this.backtrack();
        return value;
    }
    dive() {
        if (this._path.length === 0) {
            return { done: true, value: undefined };
        }
        const { node, keys } = last$1(this._path);
        if (last$1(keys) === LEAF) {
            return { done: false, value: this.result() };
        }
        const child = node.get(last$1(keys));
        this._path.push({ node: child, keys: Array.from(child.keys()) });
        return this.dive();
    }
    backtrack() {
        if (this._path.length === 0) {
            return;
        }
        const keys = last$1(this._path).keys;
        keys.pop();
        if (keys.length > 0) {
            return;
        }
        this._path.pop();
        this.backtrack();
    }
    key() {
        return this.set._prefix + this._path
            .map(({ keys }) => last$1(keys))
            .filter(key => key !== LEAF)
            .join('');
    }
    value() {
        return last$1(this._path).node.get(LEAF);
    }
    result() {
        switch (this._type) {
            case VALUES: return this.value();
            case KEYS: return this.key();
            default: return [this.key(), this.value()];
        }
    }
    [Symbol.iterator]() {
        return this;
    }
}
const last$1 = (array) => {
    return array[array.length - 1];
};

/* eslint-disable no-labels */
/**
 * @ignore
 */
const fuzzySearch = (node, query, maxDistance) => {
    const results = new Map();
    if (query === undefined)
        return results;
    // Number of columns in the Levenshtein matrix.
    const n = query.length + 1;
    // Matching terms can never be longer than N + maxDistance.
    const m = n + maxDistance;
    // Fill first matrix row and column with numbers: 0 1 2 3 ...
    const matrix = new Uint8Array(m * n).fill(maxDistance + 1);
    for (let j = 0; j < n; ++j)
        matrix[j] = j;
    for (let i = 1; i < m; ++i)
        matrix[i * n] = i;
    recurse(node, query, maxDistance, results, matrix, 1, n, '');
    return results;
};
// Modified version of http://stevehanov.ca/blog/?id=114
// This builds a Levenshtein matrix for a given query and continuously updates
// it for nodes in the radix tree that fall within the given maximum edit
// distance. Keeping the same matrix around is beneficial especially for larger
// edit distances.
//
//           k   a   t   e   <-- query
//       0   1   2   3   4
//   c   1   1   2   3   4
//   a   2   2   1   2   3
//   t   3   3   2   1  [2]  <-- edit distance
//   ^
//   ^ term in radix tree, rows are added and removed as needed
const recurse = (node, query, maxDistance, results, matrix, m, n, prefix) => {
    const offset = m * n;
    key: for (const key of node.keys()) {
        if (key === LEAF) {
            // We've reached a leaf node. Check if the edit distance acceptable and
            // store the result if it is.
            const distance = matrix[offset - 1];
            if (distance <= maxDistance) {
                results.set(prefix, [node.get(key), distance]);
            }
        }
        else {
            // Iterate over all characters in the key. Update the Levenshtein matrix
            // and check if the minimum distance in the last row is still within the
            // maximum edit distance. If it is, we can recurse over all child nodes.
            let i = m;
            for (let pos = 0; pos < key.length; ++pos, ++i) {
                const char = key[pos];
                const thisRowOffset = n * i;
                const prevRowOffset = thisRowOffset - n;
                // Set the first column based on the previous row, and initialize the
                // minimum distance in the current row.
                let minDistance = matrix[thisRowOffset];
                const jmin = Math.max(0, i - maxDistance - 1);
                const jmax = Math.min(n - 1, i + maxDistance);
                // Iterate over remaining columns (characters in the query).
                for (let j = jmin; j < jmax; ++j) {
                    const different = char !== query[j];
                    // It might make sense to only read the matrix positions used for
                    // deletion/insertion if the characters are different. But we want to
                    // avoid conditional reads for performance reasons.
                    const rpl = matrix[prevRowOffset + j] + +different;
                    const del = matrix[prevRowOffset + j + 1] + 1;
                    const ins = matrix[thisRowOffset + j] + 1;
                    const dist = matrix[thisRowOffset + j + 1] = Math.min(rpl, del, ins);
                    if (dist < minDistance)
                        minDistance = dist;
                }
                // Because distance will never decrease, we can stop. There will be no
                // matching child nodes.
                if (minDistance > maxDistance) {
                    continue key;
                }
            }
            recurse(node.get(key), query, maxDistance, results, matrix, i, n, prefix + key);
        }
    }
};

/* eslint-disable no-labels */
/**
 * A class implementing the same interface as a standard JavaScript
 * [`Map`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map)
 * with string keys, but adding support for efficiently searching entries with
 * prefix or fuzzy search. This class is used internally by {@link MiniSearch}
 * as the inverted index data structure. The implementation is a radix tree
 * (compressed prefix tree).
 *
 * Since this class can be of general utility beyond _MiniSearch_, it is
 * exported by the `minisearch` package and can be imported (or required) as
 * `minisearch/SearchableMap`.
 *
 * @typeParam T  The type of the values stored in the map.
 */
class SearchableMap {
    /**
     * The constructor is normally called without arguments, creating an empty
     * map. In order to create a {@link SearchableMap} from an iterable or from an
     * object, check {@link SearchableMap.from} and {@link
     * SearchableMap.fromObject}.
     *
     * The constructor arguments are for internal use, when creating derived
     * mutable views of a map at a prefix.
     */
    constructor(tree = new Map(), prefix = '') {
        this._size = undefined;
        this._tree = tree;
        this._prefix = prefix;
    }
    /**
     * Creates and returns a mutable view of this {@link SearchableMap},
     * containing only entries that share the given prefix.
     *
     * ### Usage:
     *
     * ```javascript
     * let map = new SearchableMap()
     * map.set("unicorn", 1)
     * map.set("universe", 2)
     * map.set("university", 3)
     * map.set("unique", 4)
     * map.set("hello", 5)
     *
     * let uni = map.atPrefix("uni")
     * uni.get("unique") // => 4
     * uni.get("unicorn") // => 1
     * uni.get("hello") // => undefined
     *
     * let univer = map.atPrefix("univer")
     * univer.get("unique") // => undefined
     * univer.get("universe") // => 2
     * univer.get("university") // => 3
     * ```
     *
     * @param prefix  The prefix
     * @return A {@link SearchableMap} representing a mutable view of the original
     * Map at the given prefix
     */
    atPrefix(prefix) {
        if (!prefix.startsWith(this._prefix)) {
            throw new Error('Mismatched prefix');
        }
        const [node, path] = trackDown(this._tree, prefix.slice(this._prefix.length));
        if (node === undefined) {
            const [parentNode, key] = last(path);
            for (const k of parentNode.keys()) {
                if (k !== LEAF && k.startsWith(key)) {
                    const node = new Map();
                    node.set(k.slice(key.length), parentNode.get(k));
                    return new SearchableMap(node, prefix);
                }
            }
        }
        return new SearchableMap(node, prefix);
    }
    /**
     * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/clear
     */
    clear() {
        this._size = undefined;
        this._tree.clear();
    }
    /**
     * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/delete
     * @param key  Key to delete
     */
    delete(key) {
        this._size = undefined;
        return remove(this._tree, key);
    }
    /**
     * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/entries
     * @return An iterator iterating through `[key, value]` entries.
     */
    entries() {
        return new TreeIterator(this, ENTRIES);
    }
    /**
     * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/forEach
     * @param fn  Iteration function
     */
    forEach(fn) {
        for (const [key, value] of this) {
            fn(key, value, this);
        }
    }
    /**
     * Returns a Map of all the entries that have a key within the given edit
     * distance from the search key. The keys of the returned Map are the matching
     * keys, while the values are two-element arrays where the first element is
     * the value associated to the key, and the second is the edit distance of the
     * key to the search key.
     *
     * ### Usage:
     *
     * ```javascript
     * let map = new SearchableMap()
     * map.set('hello', 'world')
     * map.set('hell', 'yeah')
     * map.set('ciao', 'mondo')
     *
     * // Get all entries that match the key 'hallo' with a maximum edit distance of 2
     * map.fuzzyGet('hallo', 2)
     * // => Map(2) { 'hello' => ['world', 1], 'hell' => ['yeah', 2] }
     *
     * // In the example, the "hello" key has value "world" and edit distance of 1
     * // (change "e" to "a"), the key "hell" has value "yeah" and edit distance of 2
     * // (change "e" to "a", delete "o")
     * ```
     *
     * @param key  The search key
     * @param maxEditDistance  The maximum edit distance (Levenshtein)
     * @return A Map of the matching keys to their value and edit distance
     */
    fuzzyGet(key, maxEditDistance) {
        return fuzzySearch(this._tree, key, maxEditDistance);
    }
    /**
     * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/get
     * @param key  Key to get
     * @return Value associated to the key, or `undefined` if the key is not
     * found.
     */
    get(key) {
        const node = lookup(this._tree, key);
        return node !== undefined ? node.get(LEAF) : undefined;
    }
    /**
     * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/has
     * @param key  Key
     * @return True if the key is in the map, false otherwise
     */
    has(key) {
        const node = lookup(this._tree, key);
        return node !== undefined && node.has(LEAF);
    }
    /**
     * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/keys
     * @return An `Iterable` iterating through keys
     */
    keys() {
        return new TreeIterator(this, KEYS);
    }
    /**
     * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/set
     * @param key  Key to set
     * @param value  Value to associate to the key
     * @return The {@link SearchableMap} itself, to allow chaining
     */
    set(key, value) {
        if (typeof key !== 'string') {
            throw new Error('key must be a string');
        }
        this._size = undefined;
        const node = createPath(this._tree, key);
        node.set(LEAF, value);
        return this;
    }
    /**
     * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/size
     */
    get size() {
        if (this._size) {
            return this._size;
        }
        /** @ignore */
        this._size = 0;
        const iter = this.entries();
        while (!iter.next().done)
            this._size += 1;
        return this._size;
    }
    /**
     * Updates the value at the given key using the provided function. The function
     * is called with the current value at the key, and its return value is used as
     * the new value to be set.
     *
     * ### Example:
     *
     * ```javascript
     * // Increment the current value by one
     * searchableMap.update('somekey', (currentValue) => currentValue == null ? 0 : currentValue + 1)
     * ```
     *
     * If the value at the given key is or will be an object, it might not require
     * re-assignment. In that case it is better to use `fetch()`, because it is
     * faster.
     *
     * @param key  The key to update
     * @param fn  The function used to compute the new value from the current one
     * @return The {@link SearchableMap} itself, to allow chaining
     */
    update(key, fn) {
        if (typeof key !== 'string') {
            throw new Error('key must be a string');
        }
        this._size = undefined;
        const node = createPath(this._tree, key);
        node.set(LEAF, fn(node.get(LEAF)));
        return this;
    }
    /**
     * Fetches the value of the given key. If the value does not exist, calls the
     * given function to create a new value, which is inserted at the given key
     * and subsequently returned.
     *
     * ### Example:
     *
     * ```javascript
     * const map = searchableMap.fetch('somekey', () => new Map())
     * map.set('foo', 'bar')
     * ```
     *
     * @param key  The key to update
     * @param initial  A function that creates a new value if the key does not exist
     * @return The existing or new value at the given key
     */
    fetch(key, initial) {
        if (typeof key !== 'string') {
            throw new Error('key must be a string');
        }
        this._size = undefined;
        const node = createPath(this._tree, key);
        let value = node.get(LEAF);
        if (value === undefined) {
            node.set(LEAF, value = initial());
        }
        return value;
    }
    /**
     * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/values
     * @return An `Iterable` iterating through values.
     */
    values() {
        return new TreeIterator(this, VALUES);
    }
    /**
     * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/@@iterator
     */
    [Symbol.iterator]() {
        return this.entries();
    }
    /**
     * Creates a {@link SearchableMap} from an `Iterable` of entries
     *
     * @param entries  Entries to be inserted in the {@link SearchableMap}
     * @return A new {@link SearchableMap} with the given entries
     */
    static from(entries) {
        const tree = new SearchableMap();
        for (const [key, value] of entries) {
            tree.set(key, value);
        }
        return tree;
    }
    /**
     * Creates a {@link SearchableMap} from the iterable properties of a JavaScript object
     *
     * @param object  Object of entries for the {@link SearchableMap}
     * @return A new {@link SearchableMap} with the given entries
     */
    static fromObject(object) {
        return SearchableMap.from(Object.entries(object));
    }
}
const trackDown = (tree, key, path = []) => {
    if (key.length === 0 || tree == null) {
        return [tree, path];
    }
    for (const k of tree.keys()) {
        if (k !== LEAF && key.startsWith(k)) {
            path.push([tree, k]); // performance: update in place
            return trackDown(tree.get(k), key.slice(k.length), path);
        }
    }
    path.push([tree, key]); // performance: update in place
    return trackDown(undefined, '', path);
};
const lookup = (tree, key) => {
    if (key.length === 0 || tree == null) {
        return tree;
    }
    for (const k of tree.keys()) {
        if (k !== LEAF && key.startsWith(k)) {
            return lookup(tree.get(k), key.slice(k.length));
        }
    }
};
// Create a path in the radix tree for the given key, and returns the deepest
// node. This function is in the hot path for indexing. It avoids unnecessary
// string operations and recursion for performance.
const createPath = (node, key) => {
    const keyLength = key.length;
    outer: for (let pos = 0; node && pos < keyLength;) {
        for (const k of node.keys()) {
            // Check whether this key is a candidate: the first characters must match.
            if (k !== LEAF && key[pos] === k[0]) {
                const len = Math.min(keyLength - pos, k.length);
                // Advance offset to the point where key and k no longer match.
                let offset = 1;
                while (offset < len && key[pos + offset] === k[offset])
                    ++offset;
                const child = node.get(k);
                if (offset === k.length) {
                    // The existing key is shorter than the key we need to create.
                    node = child;
                }
                else {
                    // Partial match: we need to insert an intermediate node to contain
                    // both the existing subtree and the new node.
                    const intermediate = new Map();
                    intermediate.set(k.slice(offset), child);
                    node.set(key.slice(pos, pos + offset), intermediate);
                    node.delete(k);
                    node = intermediate;
                }
                pos += offset;
                continue outer;
            }
        }
        // Create a final child node to contain the final suffix of the key.
        const child = new Map();
        node.set(key.slice(pos), child);
        return child;
    }
    return node;
};
const remove = (tree, key) => {
    const [node, path] = trackDown(tree, key);
    if (node === undefined) {
        return;
    }
    node.delete(LEAF);
    if (node.size === 0) {
        cleanup(path);
    }
    else if (node.size === 1) {
        const [key, value] = node.entries().next().value;
        merge(path, key, value);
    }
};
const cleanup = (path) => {
    if (path.length === 0) {
        return;
    }
    const [node, key] = last(path);
    node.delete(key);
    if (node.size === 0) {
        cleanup(path.slice(0, -1));
    }
    else if (node.size === 1) {
        const [key, value] = node.entries().next().value;
        if (key !== LEAF) {
            merge(path.slice(0, -1), key, value);
        }
    }
};
const merge = (path, key, value) => {
    if (path.length === 0) {
        return;
    }
    const [node, nodeKey] = last(path);
    node.set(nodeKey + key, value);
    node.delete(nodeKey);
};
const last = (array) => {
    return array[array.length - 1];
};

module.exports = SearchableMap;
//# sourceMappingURL=SearchableMap.cjs.map
