import * as vscode from 'vscode';
import { CompletionStrategy } from './CompletionStrategy';

export class LocalContextCompletion implements CompletionStrategy {
    public async provideCompletions(document: vscode.TextDocument, position: vscode.Position, linePrefix: string): Promise<vscode.CompletionItem[] | undefined> {
        const text = document.getText();
        const items: vscode.CompletionItem[] = [];

        // 1. WENN DER USER NACH EINEM PUNKT TIPPT (Cross-File Lookup)
        const dotMatch = linePrefix.match(/\b([a-zA-Z0-9_]+)\.$/);
        if (dotMatch) {
            const prefix = dotMatch[1]; // z.B. "modelling"
            if (prefix === 'log' || prefix === 'discovery') return undefined; // Built-ins ignorieren

            // Prüfen, ob der Präfix importiert wurde
            const importRegex = new RegExp(`from\\s+([a-zA-Z0-9_.]+)\\s+import\\s+${prefix}\\b`);
            const match = importRegex.exec(text);
            if (match) {
                const moduleName = match[1]; // z.B. "Company.software_modelling"
                const externalItems = await this.resolveImportedMethods(moduleName, prefix);
                return externalItems; // Nur externe Methoden zurückgeben
            }
            return undefined; // Unbekannter Namespace
        }
        
        // 2. LOKALE DEFINITIONS & IMPORTS PARSEN
        const lines = text.split('\n');
        let currentDefBlock = "";
        
        for (let i = 0; i < lines.length; i++) {
            const line = lines[i];
            const defBlockMatch = line.match(/^\s*definitions?\s+([a-zA-Z0-9_]+)/);
            if (defBlockMatch) { currentDefBlock = defBlockMatch[1]; continue; }
            if (line.match(/^\s*end\s+definitions?/)) { currentDefBlock = ""; continue; }

            const defineMatch = line.match(/^\s*define\s+([a-zA-Z0-9_]+)\b/);
            if (defineMatch) {
                const funcName = defineMatch[1];
                const fullName = currentDefBlock ? `${currentDefBlock}.${funcName}` : funcName;
                const item = new vscode.CompletionItem(fullName, vscode.CompletionItemKind.Function);
                item.detail = currentDefBlock ? `Local Function in '${currentDefBlock}'` : `Local Function`;
                item.insertText = new vscode.SnippetString(`${fullName}(\${1:params});$0`);
                items.push(item);
            }
        }

        // Imports für die globale Worterkennung bereitstellen
        const fromImportRegex = /from\s+([a-zA-Z0-9_.]+)\s+import\s+([a-zA-Z0-9_]+)/g;
        let matchVar;
        while ((matchVar = fromImportRegex.exec(text)) !== null) {
            const item = new vscode.CompletionItem(matchVar[2], vscode.CompletionItemKind.Module);
            item.detail = `Imported Definitions from ${matchVar[1]}`;
            items.push(item);
        }

        const varRegex = /([a-zA-Z0-9_]+)\s*:=/g;
        const foundVars = new Set<string>();
        while ((matchVar = varRegex.exec(text)) !== null) {
            if (matchVar[1] !== 'host') { foundVars.add(matchVar[1]); }
        }
        for (const v of foundVars) {
            items.push(new vscode.CompletionItem(v, vscode.CompletionItemKind.Variable));
        }

        return items;
    }

    // Hilfsmethode: Sucht im Workspace nach der anderen Datei!
    private async resolveImportedMethods(moduleName: string, defBlockName: string): Promise<vscode.CompletionItem[]> {
        const items: vscode.CompletionItem[] = [];
        // Sucht alle .tpl Dateien im Projekt
        const files = await vscode.workspace.findFiles('**/*.tpl', '**/node_modules/**');
        
        for (const file of files) {
            const doc = await vscode.workspace.openTextDocument(file);
            const text = doc.getText();
            
            // Ist das das gesuchte Modul? (Punkte escapen)
            const moduleRegex = new RegExp(`tpl\\s+1\\.\\d+\\s+module\\s+${moduleName.replace(/\./g, '\\.')}\\s*;`);
            if (moduleRegex.test(text)) {
                // Modul gefunden! Jetzt die Defines im entsprechenden Block auslesen
                const lines = text.split('\n');
                let inTargetBlock = false;
                for (const line of lines) {
                    if (line.match(new RegExp(`^\\s*definitions?\\s+${defBlockName}\\b`))) { inTargetBlock = true; continue; }
                    if (inTargetBlock && line.match(/^\s*end\s+definitions?/)) { inTargetBlock = false; break; }
                    
                    if (inTargetBlock) {
                        const defineMatch = line.match(/^\s*define\s+([a-zA-Z0-9_]+)\b/);
                        if (defineMatch) {
                            const funcName = defineMatch[1];
                            const item = new vscode.CompletionItem(funcName, vscode.CompletionItemKind.Function);
                            item.detail = `Method from ${moduleName}`;
                            item.insertText = new vscode.SnippetString(`${funcName}(\${1:params});$0`);
                            items.push(item);
                        }
                    }
                }
                break; // Datei gefunden und geparst, wir können abbrechen
            }
        }
        return items;
    }
}