module reggae.rules.common;


import reggae.from;
import reggae.build;
import reggae.ctaa;
import reggae.types;
import std.algorithm;
import std.path;
import std.array: array;
import std.traits;
import std.typecons;

/**
 This template function exists so as to be referenced in a reggaefile.d
 at top-level without being called via $(D alias). That way it can be
 named and used in a further $(D Target) definition without the need to
 define a function returning $(D Build).
 This function gets the source files to be compiled at runtime by searching
 for source files in the given directories, adding files and filtering
 as appropriate by the parameters given in $(D sources), its first compile-time
 parameter. The other parameters are self-explanatory.

 This function returns a list of targets that are the result of compiling
 source files written in the supported languages. The $(Sources) function
 can be used to specify source directories and source files, as well as
 a filter function to select those files that are actually wanted.
 */
Target[] objectFiles(alias sourcesFunc = Sources!(),
                     Flags flags = Flags(),
                     ImportPaths includes = ImportPaths(),
                     StringImportPaths stringImports = StringImportPaths(),
    )() @trusted {

    import std.stdio;
    const srcFiles = sourcesToFileNames!(sourcesFunc);
    return srcFilesToObjectTargets(srcFiles, flags, includes, stringImports);
}


/**
 An object file, typically from one source file in a certain language
 (although for D the default is a whole package). The language is determined
 by the file extension of the file passed in.
 The $(D projDir) variable is best left alone; right now only the dub targets
 make use of it (since dub packages are by definition outside of the project
 source tree).
*/
Target objectFile(in SourceFile srcFile,
                  in Flags flags = Flags(),
                  in ImportPaths includePaths = ImportPaths(),
                  in StringImportPaths stringImportPaths = StringImportPaths(),
                  Target[] implicits = [],
                  in string projDir = "$project")
    @safe pure
{

    import reggae.options: Options;

    auto cmd = compileCommand(srcFile.value, flags.value, includePaths.value, stringImportPaths.value, projDir);

    // try
    //     implicits ~= Target(compilerPath(Options.init, getLanguage(srcFile.value)));
    // catch(Exception _) {}

    return Target(
        srcFile.value.objFileName,
        cmd,
        [Target(srcFile.value)],
        implicits,
    );
}


// private string compilerPath(in from!"reggae.options".Options options, in Language language) @safe pure {
//     import std.process: executeShell;

//     version(Windows)
//         const cmd = "where";
//     else
//         const cmd = "which";

//     const result = executeShell(cmd ~ " " ~ compiler(options, language));

//     if(result.status != 0) throw new Exception("Could not determine the path of the compiler");

//     return result.output;
// }

// private string compiler(in from!"reggae.options".Options options, in Language language) @safe pure {
//     final switch(language) with(Language) {
//         case D:
//             return options.dCompiler;
//         case Cplusplus:
//             return options.cppCompiler;
//         case C:
//             return options.cCompiler;
//         case unknown:
//             throw new Exception("Unsupported language for compiling");
//     }
// }


/**
 A binary executable. The same as calling objectFiles and link
 with these parameters.
 */
Target executable(ExeName exeName,
                  alias sourcesFunc = Sources!(),
                  Flags compilerFlags = Flags(),
                  ImportPaths includes = ImportPaths(),
                  StringImportPaths stringImports = StringImportPaths(),
                  Flags linkerFlags = Flags())
    () {
    auto objs = objectFiles!(sourcesFunc, compilerFlags, includes, stringImports);
    return link!(exeName, { return objs; }, linkerFlags);
}

Target executable(in string projectPath,
                  in string name,
                  in string[] srcDirs,
                  in string[] excDirs,
                  in string[] srcFiles,
                  in string[] excFiles,
                  in string compilerFlags,
                  in string linkerFlags,
                  in string[] includes,
                  in string[] stringImports)
{
    auto objs = objectFiles(projectPath, srcDirs, excDirs, srcFiles, excFiles, compilerFlags, includes, stringImports);
    return link(ExeName(name), objs, Flags(linkerFlags));
}



/**
 "Compile-time" link function.
 Its parameters are compile-time so that it can be aliased and used
 at global scope in a reggafile.
 Links an executable from the given dependency targets. The linker used
 depends on the file extension of the leaf nodes of the passed-in targets.
 If any D files are found, the linker is the D compiler, and so on with
 C++ and C. If none of those apply, the D compiler is used.
 */
Target link(ExeName exeName, alias dependenciesFunc, Flags flags = Flags())() {
    auto dependencies = dependenciesFunc();
    return link(exeName, dependencies, flags);
}

/**
 Regular run-time link function.
 Links an executable from the given dependency targets. The linker used
 depends on the file extension of the leaf nodes of the passed-in targets.
 If any D files are found, the linker is the D compiler, and so on with
 C++ and C. If none of those apply, the D compiler is used.
 */
Target link(in ExeName exeName, Target[] dependencies, in Flags flags = Flags()) @safe pure {
    auto command = Command(CommandType.link,
                           assocList([assocEntry("flags", flags.value.splitter.array)]));
    return Target(exeName.value, command, dependencies);
}


/**
 Convenience rule for creating static libraries
 */
Target[] staticLibrary(string name,
                       alias sourcesFunc = Sources!(),
                       Flags flags = Flags(),
                       ImportPaths includes = ImportPaths(),
                       StringImportPaths stringImports = StringImportPaths(),
                       alias dependenciesFunc = () { Target[] ts; return ts; })
    ()
{

    version(Posix)
        return staticLibraryTarget(name, objectFiles!(sourcesFunc, flags, includes, stringImports)() ~ dependenciesFunc());
    else
        throw new Exception("Can only create static libraries on Posix");
}

/**
 "Compile-time" target creation.
 Its parameters are compile-time so that it can be aliased and used
 at global scope in a reggaefile
 */
Target target(alias outputs,
              alias command = "",
              alias dependenciesFunc = () { Target[] ts; return ts; },
              alias implicitsFunc = () { Target[] ts; return ts; })() @trusted {

    auto depsRes = dependenciesFunc();
    auto impsRes = implicitsFunc();

    static if(isArray!(typeof(depsRes)))
        auto dependencies = depsRes;
    else
        auto dependencies = [depsRes];

    static if(isArray!(typeof(impsRes)))
        auto implicits = impsRes;
    else
        auto implicits = [impsRes];


    return Target(outputs, command, dependencies, implicits);
}


/**
 * Convenience alias for appending targets without calling any runtime function.
 * This replaces the need to manually define a function to return a `Build` struct
 * just to concatenate targets
 */
Target[] targetConcat(T...)() {
    Target[] ret;
    foreach(target; T) {
        static if(isCallable!target)
            ret ~= target();
        else
            ret ~= target;
    }
    return ret;
}

/**
 Compile-time version of Target.phony
 */
Target phony(string name,
             string shellCommand,
             alias dependenciesFunc = () { Target[] ts; return ts; },
             alias implicitsFunc = () { Target[] ts; return ts; })() {
    return Target.phony(name, shellCommand, arrayify!dependenciesFunc, arrayify!implicitsFunc);
}


//end of rules

private auto arrayify(alias func)() {
    import std.traits;
    auto ret = func();
    static if(isArray!(typeof(ret)))
        return ret;
    else
        return [ret];
}

auto sourcesToTargets(alias sourcesFunc = Sources!())() {
    return sourcesToFileNames!sourcesFunc.map!(a => Target(a));
}

string[] sourcesToFileNames(alias sourcesFunc = Sources!())() @trusted {
    import std.exception: enforce;
    import std.file;
    import std.path: buildNormalizedPath, buildPath;
    import std.array: array;
    import std.traits: isCallable;
    import reggae.config: options;

    auto srcs = sourcesFunc();

    DirEntry[] modules;
    foreach(dir; srcs.dirs.value.map!(a => buildPath(options.projectPath, a))) {
        enforce(isDir(dir), dir ~ " is not a directory name");
        auto entries = dirEntries(dir, SpanMode.depth);
        auto normalised = entries.map!(a => DirEntry(buildNormalizedPath(a)));

        modules ~= normalised.filter!(a => !a.isDir).array;
    }

    foreach(module_; srcs.files.value) {
        modules ~= DirEntry(buildNormalizedPath(buildPath(options.projectPath, module_)));
    }

    return modules.
        map!(a => a.name.removeProjectPath).
        filter!(srcs.filterFunc).
        filter!(a => a != "reggaefile.d").
        array;
}

//run-time version
string[] sourcesToFileNames(in string projectPath,
                            in string[] srcDirs,
                            const(string)[] excDirs,
                            in string[] srcFiles,
                            in string[] excFiles) @trusted {



    import std.exception: enforce;
    import std.file;
    import std.path: buildNormalizedPath, buildPath;
    import std.array: array;
    import std.traits: isCallable;

    excDirs = (excDirs ~ ".reggae").map!(a => buildPath(projectPath, a)).array;

    DirEntry[] files;
    foreach(dir; srcDirs.map!(a => buildPath(projectPath, a))) {
        enforce(isDir(dir), dir ~ " is not a directory name");

        auto entries = dirEntries(dir, SpanMode.depth)
                .map!(a => a.buildNormalizedPath)
                .filter!(a => !excDirs.canFind!(b => a.dirName.absolutePath.startsWith(b)));
        files ~= entries.map!(a => DirEntry(a)).array;
    }

    foreach(module_; srcFiles) {
        files ~= DirEntry(buildNormalizedPath(buildPath(projectPath, module_)));
    }

    return files.
        map!(a => removeProjectPath(projectPath, a.name)).
        filter!(a => !excFiles.canFind(a)).
        filter!(a => a != "reggaefile.d").
        array;
}


//run-time version
Target[] objectFiles(in string projectPath,
                     in string[] srcDirs,
                     in string[] excDirs,
                     in string[] srcFiles,
                     in string[] excFiles,
                     in string flags = "",
                     in string[] includes = [],
                     in string[] stringImports = []) @trusted {

    return srcFilesToObjectTargets(sourcesToFileNames(projectPath, srcDirs, excDirs, srcFiles, excFiles),
                                   Flags(flags),
                                   const ImportPaths(includes),
                                   const StringImportPaths(stringImports));
}

//run-time version
Target[] staticLibrary(in string projectPath,
                       in string name,
                       in string[] srcDirs,
                       in string[] excDirs,
                       in string[] srcFiles,
                       in string[] excFiles,
                       in string flags,
                       in string[] includes,
                       in string[] stringImports) @trusted {


    version(Posix)
        return staticLibraryTarget(
            name,
            objectFiles(projectPath, srcDirs, excDirs, srcFiles, excFiles, flags, includes, stringImports)
        );
    else
        throw new Exception("Can only create static libraries on Posix");
}

Target[] staticLibraryTarget(in string name, Target[] objects) @safe pure {
    import std.path: extension;
    const realName = name.extension == libExt ? name : name ~ libExt;
    auto target = Target(
        [buildPath("$builddir", realName)],
        staticLibraryShellCommand,
        objects,
    );
    return [target];
}

private enum staticLibraryShellCommand = "ar rcs $out $in";

private Target[] srcFilesToObjectTargets(in string[] srcFiles,
                                         in Flags flags,
                                         in ImportPaths includes,
                                         in StringImportPaths stringImports) {

    const dSrcs = srcFiles.filter!(a => a.getLanguage == Language.D).array;
    auto otherSrcs = srcFiles.filter!(a => a.getLanguage != Language.D && a.getLanguage != Language.unknown);
    import reggae.rules.d: dlangObjectFiles;
    return
        dlangObjectFiles(dSrcs, flags.value, ["."] ~ includes.value, stringImports.value) ~
        otherSrcs.map!(a => objectFile(SourceFile(a), flags, includes)).array;
}


version(Windows) {
    immutable objExt = ".obj";
    immutable exeExt = ".exe";
    immutable libExt = ".lib";
} else {
    immutable objExt = ".o";
    immutable exeExt = "";
    immutable libExt = ".a";
}

string objFileName(in string srcFileName) @safe pure {
    return extFileName(srcFileName, objExt);
}

string libFileName(in string srcFileName) @safe pure {
    return extFileName(srcFileName, libExt);
}


string extFileName(in string srcFileName, in string extension) @safe pure {
    import reggae.path: deabsolutePath;
    import std.path: stripExtension;
    import std.array: replace;

    auto tmp = srcFileName
        .deabsolutePath
        .stripExtension
        ;

    return (tmp ~ extension).replace("..", "__");
}


string removeProjectPath(in string path) @safe {
    import std.path: relativePath, absolutePath;
    import reggae.config: options;
    //relativePath is @system
    return () @trusted { return path.absolutePath.relativePath(options.projectPath.absolutePath); }();
}

string removeProjectPath(in string projectPath, in string path) @safe pure {
    import std.path: relativePath, absolutePath;
    //relativePath is @system
    return () @trusted { return path.absolutePath.relativePath(projectPath.absolutePath); }();
}



Command compileCommand(in string srcFileName,
                       in string flags = "",
                       in string[] includePaths = [],
                       in string[] stringImportPaths = [],
                       in string projDir = "$project",
                       Flag!"justCompile" justCompile = Yes.justCompile)
    @safe pure
{

    string maybeExpand(string path) {
        return path.startsWith(gBuilddir)
            ? expandBuildDir(path)
            : buildPath(projDir, path);
    }

    auto includeParams = includePaths.map!(a => "-I" ~ maybeExpand(a)). array;
    auto flagParams = flags.splitter.array;
    immutable language = getLanguage(srcFileName);

    auto params = [
        assocEntry("includes", includeParams),
        assocEntry("flags", flagParams)
    ];

    if(language == Language.D)
        params ~= assocEntry("stringImports",
                             stringImportPaths.map!(a => "-J" ~ maybeExpand(a)).array);

    params ~= assocEntry("DEPFILE", [srcFileName.objFileName ~ ".dep"]);

    immutable type = justCompile ? CommandType.compile : CommandType.compileAndLink;
    return Command(type, assocList(params));
}


enum Language {
    C,
    Cplusplus,
    D,
    unknown,
}

Language getLanguage(in string srcFileName) @safe pure nothrow {
    switch(srcFileName.extension) with(Language) {
    case ".d":
        return D;
    case ".cpp":
    case ".CPP":
    case ".C":
    case ".cxx":
    case ".c++":
    case ".cc":
        return Cplusplus;
    case ".c":
        return C;
    default:
        return unknown;
    }
}