import * as vscode from 'vscode';
import { LinterRule } from './LinterRule';
import { LinterContext } from '../LinterContext';

export class SyntaxRule implements LinterRule {
    
    public checkLine(line: string, rawLine: string, lineIdx: number, ctx: LinterContext, lines: string[]): void {
        this.checkTabs(rawLine, lineIdx, ctx);

        // TODOs finden (blauer Info-Hinweis)
        const todoMatch = rawLine.match(/\bTODO\s*:(.*)/i);
        if (todoMatch) {
            ctx.addDiag(lineIdx, todoMatch.index!, rawLine.length, `TODO: ${todoMatch[1].trim()}`, vscode.DiagnosticSeverity.Information);
        }

        let cleanLine = line.replace(/"(?:\\.|[^"\\])*"|'(?:\\.|[^'\\])*'/g, '""');
        const commentIdx = cleanLine.indexOf('//');
        let codePart = commentIdx !== -1 ? cleanLine.substring(0, commentIdx).trim() : cleanLine.trim();

        if (codePart.length === 0) return;

        let isStructuralKeyword = /^(tpl|pattern|syncmapping|table|definitions?|define|enumeration|configuration|metadata|overview|constants|triggers|mapping|removal|body|end|on|tags|origin|author|products|publishers|tree_path|import|from)\b/.test(codePart);
        
        if (codePart.startsWith('"') || codePart.startsWith("'")) {
            isStructuralKeyword = true;
        }
        
        const isValidExecutionArea = 
            ctx.activePhaseName === 'body' || 
            ctx.activePhaseName === 'triggers' || 
            ctx.activePhaseName === 'constants' || 
            ctx.activePhaseName === 'overview' || 
            ctx.activePhaseName === 'mapping' || 
            ctx.activePhaseName === 'metadata' || 
            ctx.inModuleMetadata ||
            ctx.inBlock === 'table' || 
            ctx.inBlock === 'definitions' || 
            ctx.openDefines.length > 0;

        // 'then' und 'do' auf alleinstehenden Zeilen sind legitimer Code
        if (!isStructuralKeyword && !isValidExecutionArea && !/^(then|do)\b/.test(codePart)) {
            ctx.addDiag(lineIdx, 0, rawLine.length, "Ausführbarer Code ist hier nicht erlaubt. (Erlaubt in: 'body', 'triggers', 'constants', 'overview', 'mapping', 'metadata', 'definitions' oder 'define').", vscode.DiagnosticSeverity.Error);
        }

        this.checkBrackets(codePart, rawLine, lineIdx, ctx);
        this.checkAssignments(codePart, rawLine, lineIdx, ctx);
        this.checkSemicolons(codePart, rawLine, lineIdx, ctx, line);
    }

    public checkEnd(lines: string[], ctx: LinterContext): void {
        for (const unclosedLine of ctx.parenStack) { ctx.addDiag(unclosedLine, 0, lines[unclosedLine].length, "Öffnende Klammer '(' wird nicht geschlossen!", vscode.DiagnosticSeverity.Error); }
        for (const unclosedLine of ctx.bracketStack) { ctx.addDiag(unclosedLine, 0, lines[unclosedLine].length, "Öffnende eckige Klammer '[' wird nicht geschlossen!", vscode.DiagnosticSeverity.Error); }
    }

    private checkTabs(rawLine: string, lineIdx: number, ctx: LinterContext) {
        const tabIndex = rawLine.indexOf('\t');
        if (tabIndex !== -1) {
            const diag = ctx.addDiag(lineIdx, tabIndex, tabIndex + 1, "Bitte Tabs durch Spaces ersetzen", vscode.DiagnosticSeverity.Warning);
            diag.code = 'invalid_tab'; 
        }
    }

    private checkBrackets(codePart: string, rawLine: string, lineIdx: number, ctx: LinterContext) {
        for (let charIdx = 0; charIdx < codePart.length; charIdx++) {
            const char = codePart[charIdx];
            if (char === '(') { ctx.parenStack.push(lineIdx); } 
            else if (char === ')') {
                if (ctx.parenStack.length > 0) { ctx.parenStack.pop(); } 
                else { ctx.addDiag(lineIdx, 0, rawLine.length, "Unerwartete schließende Klammer ')'. Es fehlt eine öffnende Klammer.", vscode.DiagnosticSeverity.Error); }
            }
            else if (char === '[') { ctx.bracketStack.push(lineIdx); }
            else if (char === ']') {
                if (ctx.bracketStack.length > 0) { ctx.bracketStack.pop(); }
                else { ctx.addDiag(lineIdx, 0, rawLine.length, "Unerwartete schließende eckige Klammer ']'. Es fehlt eine öffnende Klammer.", vscode.DiagnosticSeverity.Error); }
            }
        }
    }

    private checkAssignments(codePart: string, rawLine: string, lineIdx: number, ctx: LinterContext) {
        if (/\b(if|elif|where)\b/.test(codePart)) { ctx.inConditionBlock = true; }

        if (codePart.includes('=') && !codePart.includes(':=') && !codePart.includes('>=') && !codePart.includes('<=')) {
            if (!ctx.inConditionBlock && ctx.parenStack.length === 0 && ctx.bracketStack.length === 0 && !/\b(matches)\b/.test(codePart)) {
                const idx = rawLine.indexOf('='); 
                if (idx !== -1) {
                    ctx.addDiag(lineIdx, idx, idx + 1, "Falsche Zuweisung. In TPL wird ':=' für Zuweisungen genutzt.", vscode.DiagnosticSeverity.Error);
                }
            }
        }

        if (/\b(then|do)\b/.test(codePart) || codePart.endsWith(';')) { ctx.inConditionBlock = false; }
    }

    private checkSemicolons(codePart: string, rawLine: string, lineIdx: number, ctx: LinterContext, originalTrimmedLine: string) {
        if (ctx.isClosingString) {
            if (ctx.stringNeedsSemicolon && !originalTrimmedLine.endsWith(';')) {
                ctx.addDiag(lineIdx, Math.max(0, rawLine.length - 1), rawLine.length, "Fehlendes Semikolon am Ende der Zuweisung.", vscode.DiagnosticSeverity.Error);
            }
        } else {
            // "then" und "do" dürfen am Anfang einer Zeile stehen, ohne ein Semikolon zu erfordern
            const noSemicolonNeeded = /^(pattern|syncmapping|traverse|table|enumeration|configuration|definitions?|define|metadata|overview|constants|triggers|mapping|removal|body|end\s+|if\s+|else|elif\s+|for\s+|while\s+|then\b|do\b|\/\/|\/\*|\*)/.test(codePart);
            
            // "in" (für for-Schleifen) als gültigen Zeilenumbruch hinzugefügt
            const continuesOnNextLine = /(,|and|or|not|\+|-|\*|\/|=|:=|matches|in)$/i.test(codePart);
            
            // HIER GEFIXT: Wenn die Zeile auf 'then' oder 'do' endet, verlangt sie kein Semikolon!
            const endsWithBlockOpener = /\b(then|do)$/.test(codePart);
            
            if (!noSemicolonNeeded && !ctx.justOpenedString && ctx.parenStack.length === 0 && ctx.bracketStack.length === 0 && ctx.inBlock !== 'enumeration' && !ctx.inConditionBlock && !continuesOnNextLine && !endsWithBlockOpener) {
                if (codePart.length > 0 && !codePart.endsWith(';') && !codePart.endsWith('{') && !codePart.endsWith(',')) {
                    ctx.addDiag(lineIdx, Math.max(0, rawLine.length - 1), rawLine.length, "Fehlendes Semikolon am Ende der Anweisung.", vscode.DiagnosticSeverity.Error);
                }
            }
        }
    }
}