import { TSESTree } from "@typescript-eslint/experimental-utils";

import { createRule } from "./utils";

export = createRule({

name: "simple-indent",

meta: {

docs: {

description: "Enforce consistent indentation",

category: "Stylistic Issues",

recommended: "error",

},

messages: {

simpleIndentError: "4 space indentation expected",

},

fixable: "whitespace",

schema: [],

type: "layout",

},

defaultOptions: [],

create(context) {

const TAB_SIZE = 4;

const TAB_REGEX = /\t/g;

const sourceCode = context.getSourceCode();

const linebreaks = sourceCode.getText().match(/\r\n|[\r\n\u2028\u2029]/gu);

const checkIndent = (node: TSESTree.Program) => {

const lines = sourceCode.getLines();

const linesLen = lines.length;

let totalLen = 0;

for (let i = 0; i < linesLen; i++) {

const lineNumber = i + 1;

const line = lines[i];

const linebreaksLen = linebreaks && linebreaks[i] ? linebreaks[i].length : 1;

const lineLen = line.length + linebreaksLen;

const matches = /\S/.exec(line);

if (matches && matches.index) {

const indentEnd = matches.index;

const whitespace = line.slice(0, indentEnd);

if (!TAB_REGEX.test(whitespace)) {

totalLen += lineLen;

continue;

}

context.report({

messageId: "simpleIndentError",

node,

loc: { column: indentEnd, line: lineNumber },

fix(fixer) {

const rangeStart = totalLen;

const rangeEnd = rangeStart + indentEnd;

return fixer

.replaceTextRange([rangeStart, rangeEnd], whitespace.replace(TAB_REGEX, " ".repeat(TAB_SIZE)));

}

});

}

totalLen += lineLen;

}

};

return {

Program: checkIndent,

};

},

});