import * as fs from 'fs';
import * as path from 'path';
import * as ts from 'typescript';
import * as cheerio from 'cheerio';

describe('Global Function Exports (AST Analysis)', () => {
    const srcDir = path.resolve(__dirname, '../');
    const globalFile = path.join(srcDir, 'global.ts');

    // --- Helper: Parse Global Exports ---
    const getGlobalExports = (): Set<string> => {
        const content = fs.readFileSync(globalFile, 'utf-8');
        const sourceFile = ts.createSourceFile('global.ts', content, ts.ScriptTarget.Latest, true);
        const exports = new Set<string>();

        const visit = (node: ts.Node) => {
            // Look for: ;(global as any).funcName = ...
            if (ts.isBinaryExpression(node) &&
                node.operatorToken.kind === ts.SyntaxKind.EqualsToken) {

                let left = node.left;

                // Handle property access: (exp).funcName or exp.funcName
                if (ts.isPropertyAccessExpression(left)) {

                    // Check if expression is (global as any) or global
                    let expression: ts.Expression = left.expression;

                    // Unprap parens: ((global as any))
                    while (ts.isParenthesizedExpression(expression)) {
                        expression = expression.expression;
                    }

                    // Unwrap 'as': global as any
                    if (ts.isAsExpression(expression)) {
                        expression = expression.expression;
                    }

                    if (ts.isIdentifier(expression) && expression.text === 'global') {
                        if (ts.isIdentifier(left.name)) {
                             exports.add(left.name.text);
                        }
                    }
                }
            }
            ts.forEachChild(node, visit);
        };

        visit(sourceFile);
        return exports;
    };

    // --- Helper: Find google.script.run Calls ---
    const getFrontendCalls = (): Map<string, string> => {
        const calls = new Map<string, string>(); // functionName -> filename

        const scanDir = (dir: string) => {
            const files = fs.readdirSync(dir);
            for (const file of files) {
                const fullPath = path.join(dir, file);
                const stat = fs.statSync(fullPath);

                if (stat.isDirectory()) {
                    scanDir(fullPath);
                } else if (file.endsWith('.html')) {
                    const htmlContent = fs.readFileSync(fullPath, 'utf-8');
                    const $ = cheerio.load(htmlContent);

                    $('script').each((_, script) => {
                        const scriptContent = $(script).html();
                        if (!scriptContent) return;

                        const sourceFile = ts.createSourceFile(file + '.js', scriptContent, ts.ScriptTarget.Latest, true);

                        const visit = (node: ts.Node) => {
                            if (ts.isCallExpression(node)) {
                                // Check if this call is part of a google.script.run chain
                                const chain = analyzeChain(node.expression);
                                if (chain && chain.isGoogleScriptRun) {
                                    if (!['withSuccessHandler', 'withFailureHandler', 'withUserObject'].includes(chain.methodName)) {
                                        calls.set(chain.methodName, file);
                                    }
                                }
                            }
                            ts.forEachChild(node, visit);
                        };

                        visit(sourceFile);
                    });
                }
            }
        };

        scanDir(srcDir);
        return calls;
    };

    // Helper to analyze property access chain
    // Returns { isGoogleScriptRun: boolean, methodName: string } if valid
    const analyzeChain = (expression: ts.Expression): { isGoogleScriptRun: boolean, methodName: string } | null => {
        if (!ts.isPropertyAccessExpression(expression)) {
            return null;
        }

        if (!ts.isIdentifier(expression.name)) {
            return null;
        }

        const methodName = expression.name.text;
        let current = expression.expression;

        let depth = 0;
        let p = current;

        while (depth < 20) { // Safety break
            if (ts.isCallExpression(p)) {
                 p = p.expression;
            } else if (ts.isPropertyAccessExpression(p)) {
                // Check for google.script.run
                if (ts.isIdentifier(p.name) && p.name.text === 'run') {
                     // check exp.exp is script, exp.exp.exp is google
                     if (ts.isPropertyAccessExpression(p.expression) &&
                         ts.isIdentifier(p.expression.name) &&
                         p.expression.name.text === 'script' &&
                         ts.isIdentifier(p.expression.expression) &&
                         p.expression.expression.text === 'google') {
                             return { isGoogleScriptRun: true, methodName };
                     }
                }
                p = p.expression;
            } else {
                break;
            }
            depth++;
        }

        return null;
    };


    test('All client-side google.script.run calls must be exported in global.ts', () => {
        const globalExports = getGlobalExports();
        const frontendCalls = getFrontendCalls();
        const missingQuery: string[] = [];

        frontendCalls.forEach((filename, funcName) => {
            if (!globalExports.has(funcName)) {
                missingQuery.push(`${funcName} (called in ${filename})`);
            }
        });

        if (missingQuery.length > 0) {
            throw new Error(
                `The following backend functions are called from the frontend but missing from src/global.ts:\n` +
                missingQuery.join('\n') +
                `\n\nPlease add them to src/global.ts like: ;(global as any).${missingQuery[0].split(' ')[0]} = ...`
            );
        }
    });
});