MagicString.js

import Chunk from './Chunk.js';
import SourceMap from './SourceMap.js';
import guessIndent from './utils/guessIndent.js';
import getRelativePath from './utils/getRelativePath.js';
import isObject from './utils/isObject.js';
import getLocator from './utils/getLocator.js';
import Mappings from './utils/Mappings.js';
import Stats from './utils/Stats.js';

const warned = {
	insertLeft: false,
	insertRight: false,
	storeName: false
};

export default class MagicString {
	constructor(string, options = {}) {
		const chunk = new Chunk(0, string.length, string);

		Object.defineProperties(this, {
			original:              { writable: true, value: string },
			outro:                 { writable: true, value: '' },
			intro:                 { writable: true, value: '' },
			firstChunk:            { writable: true, value: chunk },
			lastChunk:             { writable: true, value: chunk },
			lastSearchedChunk:     { writable: true, value: chunk },
			byStart:               { writable: true, value: {} },
			byEnd:                 { writable: true, value: {} },
			filename:              { writable: true, value: options.filename },
			indentExclusionRanges: { writable: true, value: options.indentExclusionRanges },
			sourcemapLocations:    { writable: true, value: {} },
			storedNames:           { writable: true, value: {} },
			indentStr:             { writable: true, value: guessIndent(string) }
		});

		if (DEBUG) {
			Object.defineProperty(this, 'stats', { value: new Stats() });
		}

		this.byStart[0] = chunk;
		this.byEnd[string.length] = chunk;
	}

	addSourcemapLocation(char) {
		this.sourcemapLocations[char] = true;
	}

	append(content) {
		if (typeof content !== 'string') throw new TypeError('outro content must be a string');

		this.outro += content;
		return this;
	}

	appendLeft(index, content) {
		if (typeof content !== 'string') throw new TypeError('inserted content must be a string');

		if (DEBUG) this.stats.time('appendLeft');

		this._split(index);

		const chunk = this.byEnd[index];

		if (chunk) {
			chunk.appendLeft(content);
		} else {
			this.intro += content;
		}

		if (DEBUG) this.stats.timeEnd('appendLeft');
		return this;
	}

	appendRight(index, content) {
		if (typeof content !== 'string') throw new TypeError('inserted content must be a string');

		if (DEBUG) this.stats.time('appendRight');

		this._split(index);

		const chunk = this.byStart[index];

		if (chunk) {
			chunk.appendRight(content);
		} else {
			this.outro += content;
		}

		if (DEBUG) this.stats.timeEnd('appendRight');
		return this;
	}

	clone() {
		const cloned = new MagicString(this.original, { filename: this.filename });

		let originalChunk = this.firstChunk;
		let clonedChunk = (cloned.firstChunk = cloned.lastSearchedChunk = originalChunk.clone());

		while (originalChunk) {
			cloned.byStart[clonedChunk.start] = clonedChunk;
			cloned.byEnd[clonedChunk.end] = clonedChunk;

			const nextOriginalChunk = originalChunk.next;
			const nextClonedChunk = nextOriginalChunk && nextOriginalChunk.clone();

			if (nextClonedChunk) {
				clonedChunk.next = nextClonedChunk;
				nextClonedChunk.previous = clonedChunk;

				clonedChunk = nextClonedChunk;
			}

			originalChunk = nextOriginalChunk;
		}

		cloned.lastChunk = clonedChunk;

		if (this.indentExclusionRanges) {
			cloned.indentExclusionRanges = this.indentExclusionRanges.slice();
		}

		Object.keys(this.sourcemapLocations).forEach(loc => {
			cloned.sourcemapLocations[loc] = true;
		});

		return cloned;
	}

	generateDecodedMap(options) {
		options = options || {};

		const sourceIndex = 0;
		const names = Object.keys(this.storedNames);
		const mappings = new Mappings(options.hires);

		const locate = getLocator(this.original);

		if (this.intro) {
			mappings.advance(this.intro);
		}

		this.firstChunk.eachNext(chunk => {
			const loc = locate(chunk.start);

			if (chunk.intro.length) mappings.advance(chunk.intro);

			if (chunk.edited) {
				mappings.addEdit(
					sourceIndex,
					chunk.content,
					loc,
					chunk.storeName ? names.indexOf(chunk.original) : -1
				);
			} else {
				mappings.addUneditedChunk(sourceIndex, chunk, this.original, loc, this.sourcemapLocations);
			}

			if (chunk.outro.length) mappings.advance(chunk.outro);
		});

		return {
			file: options.file ? options.file.split(/[/\\]/).pop() : null,
			sources: [options.source ? getRelativePath(options.file || '', options.source) : null],
			sourcesContent: options.includeContent ? [this.original] : [null],
			names,
			mappings: mappings.raw
		};
	}

	generateMap(options) {
		return new SourceMap(this.generateDecodedMap(options));
	}

	getIndentString() {
		return this.indentStr === null ? '\t' : this.indentStr;
	}

	indent(indentStr, options) {
		const pattern = /^[^\r\n]/gm;

		if (isObject(indentStr)) {
			options = indentStr;
			indentStr = undefined;
		}

		indentStr = indentStr !== undefined ? indentStr : this.indentStr || '\t';

		if (indentStr === '') return this; // noop

		options = options || {};

		// Process exclusion ranges
		const isExcluded = {};

		if (options.exclude) {
			const exclusions =
				typeof options.exclude[0] === 'number' ? [options.exclude] : options.exclude;
			exclusions.forEach(exclusion => {
				for (let i = exclusion[0]; i < exclusion[1]; i += 1) {
					isExcluded[i] = true;
				}
			});
		}

		let shouldIndentNextCharacter = options.indentStart !== false;
		const replacer = match => {
			if (shouldIndentNextCharacter) return `${indentStr}${match}`;
			shouldIndentNextCharacter = true;
			return match;
		};

		this.intro = this.intro.replace(pattern, replacer);

		let charIndex = 0;
		let chunk = this.firstChunk;

		while (chunk) {
			const end = chunk.end;

			if (chunk.edited) {
				if (!isExcluded[charIndex]) {
					chunk.content = chunk.content.replace(pattern, replacer);

					if (chunk.content.length) {
						shouldIndentNextCharacter = chunk.content[chunk.content.length - 1] === '\n';
					}
				}
			} else {
				charIndex = chunk.start;

				while (charIndex < end) {
					if (!isExcluded[charIndex]) {
						const char = this.original[charIndex];

						if (char === '\n') {
							shouldIndentNextCharacter = true;
						} else if (char !== '\r' && shouldIndentNextCharacter) {
							shouldIndentNextCharacter = false;

							if (charIndex === chunk.start) {
								chunk.prependRight(indentStr);
							} else {
								this._splitChunk(chunk, charIndex);
								chunk = chunk.next;
								chunk.prependRight(indentStr);
							}
						}
					}

					charIndex += 1;
				}
			}

			charIndex = chunk.end;
			chunk = chunk.next;
		}

		this.outro = this.outro.replace(pattern, replacer);

		return this;
	}

	insert() {
		throw new Error('magicString.insert(...) is deprecated. Use prependRight(...) or appendLeft(...)');
	}

	insertLeft(index, content) {
		if (!warned.insertLeft) {
			console.warn('magicString.insertLeft(...) is deprecated. Use magicString.appendLeft(...) instead'); // eslint-disable-line no-console
			warned.insertLeft = true;
		}

		return this.appendLeft(index, content);
	}

	insertRight(index, content) {
		if (!warned.insertRight) {
			console.warn('magicString.insertRight(...) is deprecated. Use magicString.prependRight(...) instead'); // eslint-disable-line no-console
			warned.insertRight = true;
		}

		return this.prependRight(index, content);
	}

	move(start, end, index) {
		if (index >= start && index <= end) throw new Error('Cannot move a selection inside itself');

		if (DEBUG) this.stats.time('move');

		this._split(start);
		this._split(end);
		this._split(index);

		const first = this.byStart[start];
		const last = this.byEnd[end];

		const oldLeft = first.previous;
		const oldRight = last.next;

		const newRight = this.byStart[index];
		if (!newRight && last === this.lastChunk) return this;
		const newLeft = newRight ? newRight.previous : this.lastChunk;

		if (oldLeft) oldLeft.next = oldRight;
		if (oldRight) oldRight.previous = oldLeft;

		if (newLeft) newLeft.next = first;
		if (newRight) newRight.previous = last;

		if (!first.previous) this.firstChunk = last.next;
		if (!last.next) {
			this.lastChunk = first.previous;
			this.lastChunk.next = null;
		}

		first.previous = newLeft;
		last.next = newRight || null;

		if (!newLeft) this.firstChunk = first;
		if (!newRight) this.lastChunk = last;

		if (DEBUG) this.stats.timeEnd('move');
		return this;
	}

	overwrite(start, end, content, options) {
		if (typeof content !== 'string') throw new TypeError('replacement content must be a string');

		while (start < 0) start += this.original.length;
		while (end < 0) end += this.original.length;

		if (end > this.original.length) throw new Error('end is out of bounds');
		if (start === end)
			throw new Error('Cannot overwrite a zero-length range – use appendLeft or prependRight instead');

		if (DEBUG) this.stats.time('overwrite');

		this._split(start);
		this._split(end);

		if (options === true) {
			if (!warned.storeName) {
				console.warn('The final argument to magicString.overwrite(...) should be an options object. See https://github.com/rich-harris/magic-string'); // eslint-disable-line no-console
				warned.storeName = true;
			}

			options = { storeName: true };
		}
		const storeName = options !== undefined ? options.storeName : false;
		const contentOnly = options !== undefined ? options.contentOnly : false;

		if (storeName) {
			const original = this.original.slice(start, end);
			this.storedNames[original] = true;
		}

		const first = this.byStart[start];
		const last = this.byEnd[end];

		if (first) {
			if (end > first.end && first.next !== this.byStart[first.end]) {
				throw new Error('Cannot overwrite across a split point');
			}

			first.edit(content, storeName, contentOnly);

			if (first !== last) {
				let chunk = first.next;
				while (chunk !== last) {
					chunk.edit('', false);
					chunk = chunk.next;
				}

				chunk.edit('', false);
			}
		} else {
			// must be inserting at the end
			const newChunk = new Chunk(start, end, '').edit(content, storeName);

			// TODO last chunk in the array may not be the last chunk, if it's moved...
			last.next = newChunk;
			newChunk.previous = last;
		}

		if (DEBUG) this.stats.timeEnd('overwrite');
		return this;
	}

	prepend(content) {
		if (typeof content !== 'string') throw new TypeError('outro content must be a string');

		this.intro = content + this.intro;
		return this;
	}

	prependLeft(index, content) {
		if (typeof content !== 'string') throw new TypeError('inserted content must be a string');

		if (DEBUG) this.stats.time('insertRight');

		this._split(index);

		const chunk = this.byEnd[index];

		if (chunk) {
			chunk.prependLeft(content);
		} else {
			this.intro = content + this.intro;
		}

		if (DEBUG) this.stats.timeEnd('insertRight');
		return this;
	}

	prependRight(index, content) {
		if (typeof content !== 'string') throw new TypeError('inserted content must be a string');

		if (DEBUG) this.stats.time('insertRight');

		this._split(index);

		const chunk = this.byStart[index];

		if (chunk) {
			chunk.prependRight(content);
		} else {
			this.outro = content + this.outro;
		}

		if (DEBUG) this.stats.timeEnd('insertRight');
		return this;
	}

	remove(start, end) {
		while (start < 0) start += this.original.length;
		while (end < 0) end += this.original.length;

		if (start === end) return this;

		if (start < 0 || end > this.original.length) throw new Error('Character is out of bounds');
		if (start > end) throw new Error('end must be greater than start');

		if (DEBUG) this.stats.time('remove');

		this._split(start);
		this._split(end);

		let chunk = this.byStart[start];

		while (chunk) {
			chunk.intro = '';
			chunk.outro = '';
			chunk.edit('');

			chunk = end > chunk.end ? this.byStart[chunk.end] : null;
		}

		if (DEBUG) this.stats.timeEnd('remove');
		return this;
	}

	slice(start = 0, end = this.original.length) {
		while (start < 0) start += this.original.length;
		while (end < 0) end += this.original.length;

		let result = '';

		// find start chunk
		let chunk = this.firstChunk;
		while (chunk && (chunk.start > start || chunk.end <= start)) {
			// found end chunk before start
			if (chunk.start < end && chunk.end >= end) {
				return result;
			}

			chunk = chunk.next;
		}

		if (chunk && chunk.edited && chunk.start !== start)
			throw new Error(`Cannot use replaced character ${start} as slice start anchor.`);

		const startChunk = chunk;
		while (chunk) {
			if (chunk.intro && (startChunk !== chunk || chunk.start === start)) {
				result += chunk.intro;
			}

			const containsEnd = chunk.start < end && chunk.end >= end;
			if (containsEnd && chunk.edited && chunk.end !== end)
				throw new Error(`Cannot use replaced character ${end} as slice end anchor.`);

			const sliceStart = startChunk === chunk ? start - chunk.start : 0;
			const sliceEnd = containsEnd ? chunk.content.length + end - chunk.end : chunk.content.length;

			result += chunk.content.slice(sliceStart, sliceEnd);

			if (chunk.outro && (!containsEnd || chunk.end === end)) {
				result += chunk.outro;
			}

			if (containsEnd) {
				break;
			}

			chunk = chunk.next;
		}

		return result;
	}

	// TODO deprecate this? not really very useful
	snip(start, end) {
		const clone = this.clone();
		clone.remove(0, start);
		clone.remove(end, clone.original.length);

		return clone;
	}

	_split(index) {
		if (this.byStart[index] || this.byEnd[index]) return;

		if (DEBUG) this.stats.time('_split');

		let chunk = this.lastSearchedChunk;
		const searchForward = index > chunk.end;

		while (chunk) {
			if (chunk.contains(index)) return this._splitChunk(chunk, index);

			chunk = searchForward ? this.byStart[chunk.end] : this.byEnd[chunk.start];
		}
	}

	_splitChunk(chunk, index) {
		if (chunk.edited && chunk.content.length) {
			// zero-length edited chunks are a special case (overlapping replacements)
			const loc = getLocator(this.original)(index);
			throw new Error(
				`Cannot split a chunk that has already been edited (${loc.line}:${loc.column} – "${
					chunk.original
				}")`
			);
		}

		const newChunk = chunk.split(index);

		this.byEnd[index] = chunk;
		this.byStart[index] = newChunk;
		this.byEnd[newChunk.end] = newChunk;

		if (chunk === this.lastChunk) this.lastChunk = newChunk;

		this.lastSearchedChunk = chunk;
		if (DEBUG) this.stats.timeEnd('_split');
		return true;
	}

	toString() {
		let str = this.intro;

		let chunk = this.firstChunk;
		while (chunk) {
			str += chunk.toString();
			chunk = chunk.next;
		}

		return str + this.outro;
	}

	trimLines() {
		return this.trim('[\\r\\n]');
	}

	trim(charType) {
		return this.trimStart(charType).trimEnd(charType);
	}

	trimEnd(charType) {
		const rx = new RegExp((charType || '\\s') + '+$');

		this.outro = this.outro.replace(rx, '');
		if (this.outro.length) return this;

		let chunk = this.lastChunk;

		do {
			const end = chunk.end;
			const aborted = chunk.trimEnd(rx);

			// if chunk was trimmed, we have a new lastChunk
			if (chunk.end !== end) {
				if (this.lastChunk === chunk) {
					this.lastChunk = chunk.next;
				}

				this.byEnd[chunk.end] = chunk;
				this.byStart[chunk.next.start] = chunk.next;
				this.byEnd[chunk.next.end] = chunk.next;
			}

			if (aborted) return this;
			chunk = chunk.previous;
		} while (chunk);

		return this;
	}

	trimStart(charType) {
		const rx = new RegExp('^' + (charType || '\\s') + '+');

		this.intro = this.intro.replace(rx, '');
		if (this.intro.length) return this;

		let chunk = this.firstChunk;

		do {
			const end = chunk.end;
			const aborted = chunk.trimStart(rx);

			if (chunk.end !== end) {
				// special case...
				if (chunk === this.lastChunk) this.lastChunk = chunk.next;

				this.byEnd[chunk.end] = chunk;
				this.byStart[chunk.next.start] = chunk.next;
				this.byEnd[chunk.next.end] = chunk.next;
			}

			if (aborted) return this;
			chunk = chunk.next;
		} while (chunk);

		return this;
	}
}