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): void {
        this.checkTabs(rawLine, lineIdx, ctx);
        this.checkBrackets(line, rawLine, lineIdx, ctx);
        this.checkAssignments(rawLine, lineIdx, ctx);
        this.checkSemicolons(line, rawLine, lineIdx, ctx);
    }

    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(line: string, rawLine: string, lineIdx: number, ctx: LinterContext) {
        let cleanLine = line.replace(/"(?:\\.|[^"\\])*"|'(?:\\.|[^'\\])*'/g, ''); 
        const commentIdx = cleanLine.indexOf('//');
        if (commentIdx !== -1) { cleanLine = cleanLine.substring(0, commentIdx); }

        for (let charIdx = 0; charIdx < cleanLine.length; charIdx++) {
            const char = cleanLine[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(rawLine: string, lineIdx: number, ctx: LinterContext) {
        const lineWithoutStrings = rawLine.replace(/(["'])(?:(?=(\\?))\2.)*?\1/g, '""');
        
        if (/\b(if|elif|where)\b/.test(lineWithoutStrings)) { ctx.inConditionBlock = true; }

        if (lineWithoutStrings.includes('=') && !lineWithoutStrings.includes(':=') && !lineWithoutStrings.includes('>=') && !lineWithoutStrings.includes('<=')) {
            if (!ctx.inConditionBlock && ctx.parenStack.length === 0 && ctx.bracketStack.length === 0 && !/\b(matches)\b/.test(lineWithoutStrings)) {
                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(lineWithoutStrings) || lineWithoutStrings.endsWith(';')) { ctx.inConditionBlock = false; }
    }

    private checkSemicolons(line: string, rawLine: string, lineIdx: number, ctx: LinterContext) {
        if (ctx.isClosingString) {
            if (ctx.stringNeedsSemicolon && !line.endsWith(';')) {
                ctx.addDiag(lineIdx, Math.max(0, rawLine.length - 1), rawLine.length, "Fehlendes Semikolon am Ende der Zuweisung.", vscode.DiagnosticSeverity.Error);
            }
        } else {
            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+|\/\/|\/\*|\*)/;
            const continuesOnNextLine = /(,|and|or|not|\+|-|\*|\/|=|:=|matches)$/i.test(line);
            
            if (!noSemicolonNeeded.test(line) && !ctx.justOpenedString && ctx.parenStack.length === 0 && ctx.bracketStack.length === 0 && ctx.inBlock !== 'enumeration' && !ctx.inConditionBlock && !continuesOnNextLine) {
                const lineToCheck = line.split('//')[0].trim();
                if (!lineToCheck.endsWith(';') && !lineToCheck.endsWith('{') && !lineToCheck.endsWith(',')) {
                    ctx.addDiag(lineIdx, Math.max(0, rawLine.length - 1), rawLine.length, "Fehlendes Semikolon am Ende der Anweisung.", vscode.DiagnosticSeverity.Error);
                }
            }
        }
    }
}