package org.simantics.scl.compiler.elaboration.expressions;

import org.simantics.scl.compiler.common.exceptions.InternalCompilerError;
import org.simantics.scl.compiler.compilation.CompilationContext;
import org.simantics.scl.compiler.elaboration.contexts.ReplaceContext;
import org.simantics.scl.compiler.elaboration.contexts.SimplificationContext;
import org.simantics.scl.compiler.elaboration.contexts.TranslationContext;
import org.simantics.scl.compiler.elaboration.contexts.TypingContext;
import org.simantics.scl.compiler.errors.Locations;
import org.simantics.scl.compiler.internal.codegen.references.IVal;
import org.simantics.scl.compiler.internal.codegen.writer.CodeWriter;
import org.simantics.scl.compiler.types.Type;
import org.simantics.scl.compiler.types.exceptions.MatchException;

import gnu.trove.map.hash.TObjectIntHashMap;
import gnu.trove.set.hash.THashSet;
import gnu.trove.set.hash.TIntHashSet;

public class EAsPattern extends Expression {

    public Variable var;
    public EVar eVar;
    public Expression pattern;

    public EAsPattern(EVar eVar, Expression pattern) {
        this.eVar = eVar;
        this.pattern = pattern;
    }
    
    public EAsPattern(Variable var, Expression pattern) {
        this.var = var;
        this.pattern = pattern;
    }
    
    public Variable getVariable() {
        return var;
    }
    
    public Expression getPattern() {
        return pattern;
    }

    @Override
    public void collectVars(TObjectIntHashMap<Variable> allVars,
            TIntHashSet vars) {
        int id = allVars.get(var);
        if(id >= 0)
            vars.add(id);
        pattern.collectVars(allVars, vars);
    }

    @Override
    public void collectFreeVariables(THashSet<Variable> vars) {
        throw new InternalCompilerError(location, "Cannot collect free variables for a pattern.");
    }
    
    @Override
    public void removeFreeVariables(THashSet<Variable> vars) {
        vars.remove(var);
        pattern.removeFreeVariables(vars);
    }
    
    @Override
    public Expression simplify(SimplificationContext context) {
        pattern = pattern.simplify(context);
        return this;
    }

    @Override
    public Expression resolve(TranslationContext context) {
        context.getErrorLog().log(location, "As binding (@) can be used only in patterns.");
        return this;
    }
    
    @Override
    public Expression resolveAsPattern(TranslationContext context) {
        var = context.newVariable(eVar.name);
        pattern = pattern.resolveAsPattern(context);
        return this;
    }
    
    @Override
    protected void updateType() throws MatchException {
        setType(pattern.getType());
    }

    @Override
    public IVal toVal(CompilationContext context, CodeWriter w) {
        throw new InternalCompilerError("EAsPattern allowed only in patterns.");
    }
    
    @Override
    public Expression inferType(TypingContext context) {
        pattern = pattern.inferType(context);
        var.setType(pattern.getType());
        return this;
    }
    
    @Override
    public Expression checkBasicType(TypingContext context, Type requiredType) {
        pattern = pattern.checkBasicType(context, requiredType);
        var.setType(pattern.getType());
        return this;
    }
    
    @Override
    public Expression replace(ReplaceContext context) {
        if(!context.inPattern) 
            throw new IllegalStateException();
        
        Variable newVariable = new Variable(var.name);
        newVariable.setType(var.getType().replace(context.tvarMap));
        context.varMap.put(var, new EVariable(newVariable));
        
        EAsPattern result = new EAsPattern(eVar, pattern.replace(context));
        result.var = newVariable;
        
        return result;
    }
    
    @Override
    public void setLocationDeep(long loc) {
        if(location == Locations.NO_LOCATION) {
            location = loc;
            pattern.setLocationDeep(loc);
            if(eVar != null)
                eVar.setLocationDeep(loc);
        }
    }
    
    @Override
    public void accept(ExpressionVisitor visitor) {
        visitor.visit(this);
    }
    
    @Override
    public Expression accept(ExpressionTransformer transformer) {
        return transformer.transform(this);
    }

}