import { AttachedScope, attachScopes } from '@rollup/pluginutils';

import { Node, walk } from 'estree-walker';

import isReference from 'is-reference';

import type { AstNode } from 'rollup';

import type { MemberExpression } from 'estree';

const META_START = '// ==UserScript==';

const META_END = '// ==/UserScript==';

const GRANTS_REGEXP = /^(unsafeWindow$|GM[._]\w+)/;

export function collectGrants(ast: AstNode) {

let scope = attachScopes(ast, 'scope');

const grantSetPerFile = new Set();

walk(ast as Node, {

enter(node: Node & { scope: AttachedScope }, parent) {

if (node.scope) scope = node.scope;

if (

node.type === 'MemberExpression' &&

isReference(node, parent)

) {

const fullName = getMemberExpressionFullNameRecursive(node);

const match = GRANTS_REGEXP.exec(fullName);

if (match) {

grantSetPerFile.add(match[0]);

this.skip();

}

}

if (

node.type === 'Identifier' &&

isReference(node, parent) &&

!scope.contains(node.name)

) {

const match = GRANTS_REGEXP.exec(node.name);

if (match) {

grantSetPerFile.add(match[0]);

}

}

},

leave(node: Node & { scope: AttachedScope }) {

if (node.scope) scope = scope.parent;

},

});

return grantSetPerFile;

}

function getMemberExpressionFullNameRecursive(astNode: MemberExpression): string | null {

if (astNode.property.type !== 'Identifier') {

return null;

}

switch (astNode.object.type) {

case 'MemberExpression': {

const nameSoFar = getMemberExpressionFullNameRecursive(astNode.object);

if (nameSoFar == null) {

return null;

}

return `${nameSoFar}.${astNode.property.name}`

}

case 'Identifier': {

return `${astNode.object.name}.${astNode.property.name}`;

}

default: {

return null;

}

}

}

export function getMetadata(

metaFileContent: string,

additionalGrantList: Set<string>,

) {

const lines = metaFileContent.split('\n').map((line) => line.trim());

const start = lines.indexOf(META_START);

const end = lines.indexOf(META_END);

if (start < 0 || end < 0) {

throw new Error(

'Invalid metadata block. For more details see https://violentmonkey.github.io/api/metadata-block/',

);

}

const grantSet = new Set<string>();

const entries = lines

.slice(start + 1, end)

.map((line) => {

if (!line.startsWith('// ')) return;

line = line.slice(3).trim();

const matches = line.match(/^(\S+)(\s.*)?$/);

if (!matches) return;

const key = matches[1];

const value = (matches[2] || '').trim();

if (key === '@grant') {

grantSet.add(value);

return;

}

return [key, value];

})

.filter(Boolean);

for (const item of additionalGrantList) {

grantSet.add(item);

}

const grantList = Array.from(grantSet);

grantList.sort();

for (const item of grantList) {

entries.push(['@grant', item]);

}

const maxKeyWidth = Math.max(...entries.map(([key]) => key.length));

return [

META_START,

...entries.map(([key, value]) => `// ${key.padEnd(maxKeyWidth)} ${value}`),

META_END,

].join('\n');

}