package org.jruby.ir.persistence;

import org.jruby.RubyInstanceConfig;
import org.jruby.ir.IRMethod;
import org.jruby.ir.IRScope;
import org.jruby.ir.IRScriptBody;
import org.jruby.ir.instructions.Instr;
import org.jruby.parser.StaticScope;

import java.io.IOException;

Write IR data out to persistent store.  IRReader is capable of re-reading this
information back into live IR data again.  This class knows the logical order of how
information will be written out but the IRWriterEncoder actually knows how to encode that
information.
/**
 * Write IR data out to persistent store.  IRReader is capable of re-reading this
 * information back into live IR data again.  This class knows the logical order of how
 * information will be written out but the IRWriterEncoder actually knows how to encode that
 * information.
 */
public class IRWriter {

    private IRWriter() { /* static methods only, for now */ }

    public static void persist(IRWriterEncoder file, IRScope script) throws IOException {
        file.startEncoding(script);
        persistScopeInstructions(file, script); // recursive dump of all scopes instructions

        file.startEncodingScopeHeaders(script);
        persistScopeHeaders(file, script);      // recursive dump of all defined scope headers
        file.endEncodingScopeHeaders(script);

        file.endEncoding(script);
    }

    private static void persistScopeInstructions(IRWriterEncoder file, IRScope parent) {
        persistScopeInstrs(file, parent);

        for (IRScope scope: parent.getLexicalScopes()) {
            persistScopeInstructions(file, scope);
        }
    }

    // {operation, [operands]}*
    private static void persistScopeInstrs(IRWriterEncoder file, IRScope scope) {
        file.startEncodingScopeInstrs(scope);

        // Currently methods are only lazy scopes so we need to build them if we decide to persist them.
        if (scope instanceof IRMethod && !scope.hasBeenBuilt()) {
            ((IRMethod) scope).lazilyAcquireInterpreterContext();
        }

        for (Instr instr: scope.getInterpreterContext().getInstructions()) {
            file.encode(instr);
        }

        file.endEncodingScopeInstrs(scope);
    }

    // recursive dump of all scopes.  Each scope records offset into persisted file where there
    // instructions reside.  That is extra logic here in currentInstrIndex + instrsLocations
    private static void persistScopeHeaders(IRWriterEncoder file, IRScope parent) {
        persistScopeHeader(file, parent);

        for (IRScope scope: parent.getLexicalScopes()) {
            persistScopeHeaders(file, scope);
        }
    }

    // script body: {type,name,linenumber,{static_scope},instrs_offset}
    // closure scopes: {type,name,linenumber,lexical_parent_name, lexical_parent_line,is_for,arity,arg_type,{static_scope},instrs_offset}
    // other scopes: {type,name,linenumber,lexical_parent_name, lexical_parent_line,{static_scope}, instrs_offset}
    // for non-for scopes is_for,arity, and arg_type will be 0.
    private static void persistScopeHeader(IRWriterEncoder file, IRScope scope) {
        if (RubyInstanceConfig.IR_WRITING_DEBUG) System.out.println("Writing Scope Header");
        file.startEncodingScopeHeader(scope);
        scope.persistScopeHeader(file);

        if (RubyInstanceConfig.IR_WRITING_DEBUG) System.out.println("NAME = " + scope.getId());
        if (scope instanceof IRScriptBody) {
            file.encode(scope.getId());
        } else {
            file.encodeRaw(scope.getName());
            file.encode(scope.getLexicalParent());
        }

        persistStaticScope(file, scope.getStaticScope());
        scope.persistScopeFlags(file);
        file.endEncodingScopeHeader(scope);
    }

    // {type,[variables],signature}
    private static void persistStaticScope(IRWriterEncoder file, StaticScope staticScope) {
        file.encode(staticScope.getType());
        file.encode(staticScope.getVariables());
        file.encode(staticScope.getFirstKeywordIndex());
        file.encode(staticScope.getSignature());
    }
}