import * as vscode from 'vscode';
import { CompletionStrategy } from './CompletionStrategy';
import { tplBuiltIns } from '../../data/TplBuiltIns';
import { workspaceIndex } from '../../core/WorkspaceIndex';

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. SMART IMPORT: "from "
        if (linePrefix.match(/\bfrom\s+$/)) {
            for (const mod of workspaceIndex.getAllModules()) {
                const item = new vscode.CompletionItem(mod, vscode.CompletionItemKind.Module);
                item.detail = "Workspace Module";
                items.push(item);
            }
            return items; // Nichts anderes vorschlagen!
        }

        // 2. SMART IMPORT: "from X import "
        const importContextMatch = linePrefix.match(/\bfrom\s+([a-zA-Z0-9_.]+)\s+import\s+$/);
        if (importContextMatch) {
            const modName = importContextMatch[1];
            for (const defBlock of workspaceIndex.getDefinitionBlocksForModule(modName)) {
                const item = new vscode.CompletionItem(defBlock, vscode.CompletionItemKind.Class);
                item.detail = `Definitions from ${modName}`;
                items.push(item);
            }
            return items; // Nichts anderes vorschlagen!
        }

        // 3. NAMESPACE CALLS: "prefix."
        const dotMatch = linePrefix.match(/\b([a-zA-Z0-9_]+)\.([a-zA-Z0-9_]*)$/);
        if (dotMatch) {
            const prefix = dotMatch[1]; 
            
            // BMC Built-ins ignorieren (übernimmt BuiltInCompletion)
            const bmcNamespaces = Object.keys(tplBuiltIns);
            if (bmcNamespaces.includes(prefix)) {
                return undefined; // Hier darf undefined sein, weil BuiltInCompletion das fängt
            }

            let funcs = [];

            // A) RAM-Abfrage für importierte Module
            const importRegex = new RegExp(`from\\s+([a-zA-Z0-9_.]+)\\s+import\\s+${prefix}\\b`);
            const match = importRegex.exec(text);
            if (match) {
                const moduleName = match[1];
                // Filtere Funktionen aus dem importierten Modul, die zu diesem Prefix gehören
                funcs = workspaceIndex.getFunctionsForModule(moduleName).filter(f => f.name.startsWith(`${prefix}.`) || !f.name.includes('.'));
            } else {
                // B) Lokale Definitions in der aktuellen Datei prüfen!
                const localDefRegex = new RegExp(`^\\s*definitions?\\s+${prefix}\\b`, 'm');
                if (localDefRegex.test(text)) {
                    const lines = text.split('\n');
                    let inTargetBlock = false;
                    for (const line of lines) {
                        if (line.match(new RegExp(`^\\s*definitions?\\s+${prefix}\\b`))) { inTargetBlock = true; continue; }
                        if (line.match(/^\s*end\s+definitions?/)) { inTargetBlock = false; continue; }
                        if (inTargetBlock) {
                            const defineMatch = line.match(/^\s*define\s+([a-zA-Z0-9_]+)\b(?:\s*\((.*?)\))?/);
                            if (defineMatch) {
                                const params = (defineMatch[2] || "").split(',').map(p => p.trim()).filter(p => p.length > 0);
                                funcs.push({ name: defineMatch[1], moduleName: 'local', params: params });
                            }
                        }
                    }
                }
            }

            if (funcs.length > 0) {
                for (const f of funcs) {
                    const shortName = f.name.split('.').pop() || f.name;
                    const item = new vscode.CompletionItem(shortName, vscode.CompletionItemKind.Function);
                    item.detail = f.moduleName === 'local' ? `Local Method` : `Method from ${f.moduleName}`;
                    
                    // FIX: Dynamische Parameter-Generierung! Baut z.B. ${1:host}, ${2:ip}
                    let paramSnippet = "";
                    if (f.params && f.params.length > 0) {
                        paramSnippet = f.params.map((p, idx) => `\${${idx + 1}:${p}}`).join(', ');
                    }
                    
                    item.insertText = new vscode.SnippetString(`${shortName}(${paramSnippet});$0`);
                    items.push(item);
                }
                return items; // Gibt exakt die Funktionen zurück
            }

            // FIX: Wenn es ein unbekannter Namespace mit Punkt ist, geben wir ein leeres Array [] zurück!
            // Das zwingt VS Code dazu, KEINE generischen Textwörter vorzuschlagen.
            return []; 
        }
        
        // 4. LOKALE DEFINITIONS PARSEN (Für den globalen Scope, noch ohne Punkt aufgerufen)
        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(?:\s*\((.*?)\))?/);
            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`;
                
                // Dynamische Parameter-Generierung auch hier!
                const params = (defineMatch[2] || "").split(',').map(p => p.trim()).filter(p => p.length > 0);
                let paramSnippet = "";
                if (params.length > 0) {
                    paramSnippet = params.map((p, idx) => `\${${idx + 1}:${p}}`).join(', ');
                }

                item.insertText = new vscode.SnippetString(`${fullName}(${paramSnippet});$0`);
                items.push(item);
            }
        }

        // Import-Referenzen für den globalen Scope 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);
        }

        // Lokale Variablen (:=) vorschlagen
        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;
    }
}