import assert from "assert";
import { describe } from "mocha";
import { indentUnit } from "@codemirror/language";
import { EditorState } from "@codemirror/state";
import { detectIndentUnit, hasLineNumbers, spacesToTabStop } from "../../src/ide/views/tabs";

// Build a state from text with '|' marking the cursor; returns the spaces Tab would insert.
function tabAt(textWithCursor: string, tabSize: number, unit: number): string {
    const head = textWithCursor.indexOf('|');
    const state = EditorState.create({
        doc: textWithCursor.replace('|', ''),
        extensions: [EditorState.tabSize.of(tabSize), indentUnit.of(" ".repeat(unit))],
    });
    return spacesToTabStop(state, head);
}

describe('spacesToTabStop', () => {
    it('should advance by indent unit in leading whitespace', () => {
        assert.strictEqual(tabAt('|', 8, 2).length, 2);
        assert.strictEqual(tabAt('  |', 8, 2).length, 2);
        assert.strictEqual(tabAt('    |x', 8, 2).length, 2);
        assert.strictEqual(tabAt('   |x', 8, 2).length, 1); // 3 -> 4
    });
    it('should advance to tab size stops after text', () => {
        assert.strictEqual(tabAt('int x;|', 8, 2).length, 2); // 6 -> 8
        assert.strictEqual(tabAt('int x;  |', 8, 2).length, 8); // 8 -> 16
        assert.strictEqual(tabAt('x|', 8, 2).length, 7);
    });
    it('should use the tab size stops when indent unit equals it', () => {
        assert.strictEqual(tabAt('|', 8, 8).length, 8);
        assert.strictEqual(tabAt('  |', 8, 8).length, 6);
    });
    it('should count literal tab characters as tab size columns', () => {
        assert.strictEqual(tabAt('\t|', 8, 2).length, 2); // col 8 -> 10
        assert.strictEqual(tabAt('\tx|', 8, 2).length, 7); // col 9 -> 16
    });
    it('should use the cursor line only', () => {
        assert.strictEqual(tabAt('    foo\n|', 8, 2).length, 2);
        assert.strictEqual(tabAt('a\n  b|\nc', 4, 2).length, 1); // col 3 -> 4
    });
    it('should insert spaces only', () => {
        assert.strictEqual(tabAt('a|', 4, 2), '   ');
    });
});

describe('hasLineNumbers', () => {
    const has = (doc: string) => hasLineNumbers(EditorState.create({ doc }));
    it('should detect line-numbered BASIC', () => {
        assert.strictEqual(has('10 PRINT "HI"\n20 GOTO 10'), true);
        assert.strictEqual(has('REM start\n30 END'), true);
        assert.strictEqual(has('REM start\n3 END'), false);
        assert.strictEqual(has('REM start\n  30 END'), false);
    });
    it('should treat unnumbered source as structured', () => {
        assert.strictEqual(has(''), false);
        assert.strictEqual(has('for i = 1 to 10\n  print i\nnext'), false);
        assert.strictEqual(has('x1 = 5'), false);
    });
});

describe('detectIndentUnit', () => {
    it('should detect the most common indent step', () => {
        assert.strictEqual(detectIndentUnit('void main() {\n  int x;\n  if (x) {\n    x++;\n  }\n}\n'), '  ');
        assert.strictEqual(detectIndentUnit('void main() {\n    int x;\n    if (x) {\n        x++;\n    }\n}\n'), '    ');
        assert.strictEqual(detectIndentUnit('void main() {\n\tint x;\n\tif (x) {\n\t\tx++;\n\t}\n}\n'), '\t');
    });
    it('should ignore block comment continuations and alignment outliers', () => {
        assert.strictEqual(detectIndentUnit('/*\n * doc\n */\nvoid f() {\n    a();\n    b(1,\n              2);\n    if (x)\n        c();\n}\n'), '    ');
    });
    it('should default to two spaces', () => {
        assert.strictEqual(detectIndentUnit(''), '  ');
        assert.strictEqual(detectIndentUnit('int x;\nint y;\n'), '  ');
    });
});