package com.seaofnodes.simple.codegen;

import com.seaofnodes.simple.Parser;
import com.seaofnodes.simple.node.*;
import com.seaofnodes.simple.type.Type;
import com.seaofnodes.simple.type.TypeStruct;
import com.seaofnodes.simple.util.*;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.*;
import static com.seaofnodes.simple.codegen.CodeGen.CODE;

// A compilation-unit, which is an external reference and source and object
// files.  These are mirrored over a file system tree (so form a tree), both
// the source tree and build/object tree.
public class CompUnit {
    public final CompUnit _par;        // Parent, e.g. A/B
    final String _fname;        // Full slashed file name starting from module root, e.g. A/B/C
    final public String _cname; // Full dotted class name starting from module root, e.g. A.B.C
    final String _name;         // Base name, e.g. C
    final ExternNode _ext;      // Found in external libs; e.g. libc
    final File _smp;            // Simple source file, e.g. module_root/A/B/C.smp
    public final File _obj;            // ELF output file, e.g. build/A/B/C.o
    final public String _src;   // Source code, from file or test case
    //public Encoding _encoding;  // Encoding for output

    public TypeStruct _clz; // The one TypeStruct being published
    //BAOS _serial;           // Serialized IR for this ELF file
    Ary<CompUnit> _deps;    // CompUnits that this CompUnit depends on

    // Per-Compilation-Unit Start/StopNodes, keeping alive all exported Nodes.
    // Null means no code loaded (yet).
    public StartCUNode _start;
    public StopCUNode  _stop ;


    // Discovered source file.  Source is loaded if required to parse, and null
    // otherwise.
    CompUnit( CompUnit par, String fname, String cname, String name ) throws IOException {
        _par  = par;
        _fname= fname;
        _cname= cname;
        _name = name;
        _ext  = null;
        _smp  = new File( CODE.  _modDir + "/" + fname + ".smp");
        _obj  = new File( CODE._buildDir + "/" + fname + ".o"  );

        boolean mustCompile = _smp.exists() && // Has source to compile
            ( !_obj.exists() ||                // No object file
              _smp.lastModified() > _obj.lastModified() || // Out-of-date with source?
              checkDependentObjs() );                      // Out-of-date with other objs?
        _src  = mustCompile ? new String(Files.readAllBytes(_smp.toPath())) : null;
    }

    // Test case.  No source file.  Source code passed in as a String.  Fake
    // class name.
    CompUnit( String fname, String src ) {
        _par  = null;
        _name = fname;
        _fname= fname;
        _cname= fname;
        _ext  = null;
        _smp  = null;
        _obj  = null;
        _src  = src;
    }

    // External CompUnit, pulled in from an external library like libc
    CompUnit( ExternNode ext, String symbol ) {
        _par  = null;
        _name = symbol;
        _fname= _name;
        _cname= null;
        _ext  = ext;
        _smp  = null;
        _obj  = null;
        _src  = null;
    }

    // External Simple object file, or namespace parent, found on an external search path.
    CompUnit( File obj, CompUnit par, String fname, String cname, String name ) {
        _par  = par;
        _name = name;
        _fname= fname;
        _cname= cname;
        _ext  = null;
        _smp  = null;
        _obj  = obj;
        _src  = null;
    }

    // Return true if _obj is out-of-date relative to dependents.
    private boolean checkDependentObjs() {
        ElfReader elf = CODE.getElf(_obj);
        elf.loadPublicSymbols();
        for( String dep : elf._deps ) {
            File obj = new File(CODE._buildDir+"/"+dep+".o");
            if( obj.lastModified() > _obj.lastModified() ) // Out-of-date with deps?
                return true;
        }
        return false;
    }

    // Add a discovered dependency, for later writing out in an ELF file, ".simple" section
    void addDep(CompUnit dep) {
        if( _deps == null ) _deps = new Ary<>(CompUnit.class);
        _deps.add(dep);
    }

    public void addFun(CodeGen code, FunNode fun) {
        assert fun.in(1)==_start;
        _stop.addDef(fun.ret());
        code.add(_stop);
        _stop.addDep(fun);
    }

    void setStart(CodeGen code) {
        _stop  = new  StopCUNode().init();
        _start = new StartCUNode(code._start,_stop, Type.BOTTOM, _fname).init();
        code._stop.addDef(_stop);
    }


    @Override public String toString() {
        String x = "{"+_cname;
        if( _smp!=null && _smp.exists()) x += ",hasSMP";
        if( _obj!=null && _obj.exists()) x += ",hasObj";
        if( _src!=null   ) x += ",hasSrc";
        if( _ext != null ) x += ",isExt";
        x += "}";
        return x;
    }
}