using Invercargill;
namespace Usm {

    public class ResourceFinder {
        public Paths paths { get; set; }

        public ResourceFinder(Paths? paths = null) {
            this.paths = paths ?? new Paths();
        }

        public bool has_resource(ResourceRef resource_ref) {
            return locate_resource(resource_ref) != null;
        }

        public string? locate_resource(ResourceRef resource_ref) {
            switch (resource_ref.resource_type) {
                case ResourceType.ROOT_PATH:
                    return locate_rootpath(resource_ref);
                case ResourceType.PATH:
                    return locate_path(resource_ref);
                case ResourceType.OPTIONAL:
                    return locate_opt(resource_ref);
                case ResourceType.RESOURCE:
                    return locate_res(resource_ref);
                case ResourceType.CONFIGURATION:
                    return locate_cfg(resource_ref);
                case ResourceType.BINARY:
                    return locate_bin(resource_ref);
                case ResourceType.SUPER_BINARY:
                    return locate_sbin(resource_ref);
                case ResourceType.LIBRARY:
                    return locate_lib(resource_ref);
                case ResourceType.LIBRARY_EXECUTABLE:
                    return locate_libexec(resource_ref);
                case ResourceType.LIBRARY_RESOURCE:
                    return locate_libres(resource_ref);
                case ResourceType.CANONICAL_LIBRARY:
                    return locate_canonlib(resource_ref);
                case ResourceType.CANONICAL_LIBRARY_RESOURCE:
                    return locate_canonlibres(resource_ref);
                case ResourceType.GIO_MODULE:
                    return locate_gio(resource_ref);
                case ResourceType.INFO_PAGE:
                    return locate_info(resource_ref);
                case ResourceType.MANUAL_PAGE:
                    return locate_man(resource_ref);
                case ResourceType.LOCALE:
                    return locate_locale(resource_ref);
                case ResourceType.APPLICATION:
                    return locate_app(resource_ref);
                case ResourceType.INCLUDE:
                    return locate_inc(resource_ref);
                case ResourceType.PKG_CONFIG:
                    return locate_pc(resource_ref);
                case ResourceType.VALA_API:
                    return locate_vapi(resource_ref);
                case ResourceType.GOBJECT_IR:
                    return locate_gir(resource_ref);
                case ResourceType.TYPELIB:
                    return locate_typelib(resource_ref);
                case ResourceType.TAG:
                    return locate_tag(resource_ref);
                default:
                    assert_not_reached();
            }
        }

        private string? locate_tag(ResourceRef resource) {
            if(Tag.read(resource.resource) != null) {
                return paths.get_tag_file_path(resource.resource);
            }
            return null;
        }

        private string? locate_lib(ResourceRef resource) {
            var via_ldconfig = locate_lib_ldconfig(resource);
            if(via_ldconfig != null) {
                return via_ldconfig;
            }
            // musl systems have no `ldconfig -p` output to consult: fall
            // back to the conventional library directories
            foreach(var directory in new string[] { "/lib", "/usr/lib", "/lib64", "/usr/lib64" }) {
                var file = File.new_build_filename(directory, resource.resource);
                if(file.query_exists()) {
                    return file.get_path();
                }
            }
            return null;
        }

        private string? locate_lib_ldconfig(ResourceRef resource) {
            try {
                var proc = new Subprocess.newv(new string[] { "ldconfig", "-p" },
                    SubprocessFlags.STDOUT_PIPE | SubprocessFlags.STDERR_SILENCE);
                var pipe = new DataInputStream(proc.get_stdout_pipe());
                string line = null;
                while((line = pipe.read_line()) != null) {
                    if(line.has_prefix("\t")) {
                        var name = line.substring(1).split(" ", 2)[0];
                        if(resource.resource == name) {
                            return line.substring(1).split("=>", 2)[1].chomp().chug();
                        }
                    }
                }
                proc.wait_check();
            }
            catch(Error e) {
                // busybox/musl ldconfig doesn't support -p; the fallback in
                // locate_lib handles it — suppress the noise
            }
            return null;
        }

        private string? locate_canonlib(ResourceRef resource) {
            try {
                var proc = new Subprocess.newv(new string[] { "ldconfig", "-p" },
                    SubprocessFlags.STDOUT_PIPE | SubprocessFlags.STDERR_SILENCE);
                var pipe = new DataInputStream(proc.get_stdout_pipe());
                string line = null;
                while((line = pipe.read_line()) != null) {
                    if(line.has_prefix("\t")) {
                        var name = line.substring(1).split(" ", 2)[0];
                        // Only return true for libraries found in the canonical lib directory (e.g. not in /lib64)
                        if(resource.resource == name && (name.has_prefix("/usr/lib") || name.has_prefix("/lib"))) {
                            return line.substring(1).split("=>", 2)[1].chomp().chug();
                        }
                    }
                }
                proc.wait_check();
            }
            catch(Error e) {
                warning(@"Error checking for resource $resource: $(e.message)");
            }
            return null;
        }

        private string? locate_bin(ResourceRef resource) {
            var env_paths = Environment.get_variable("PATH").split(":");
            foreach (var path in env_paths) {
                var file = File.new_build_filename(paths.destination, path, resource.resource);
                if(file.query_exists()) {
                    return file.get_path();
                }
            }
            return null;
        }

        private string? locate_path(ResourceRef resource) {
            var file = File.new_build_filename(paths.destination, paths.prefix, resource.resource);
            return file.query_exists() ? file.get_path() : null;
        }

        private string? locate_rootpath(ResourceRef resource) {
            var file = File.new_build_filename(paths.destination, resource.resource);
            return file.query_exists() ? file.get_path() : null;
        }

        private string? locate_res(ResourceRef resource) {
            var file = File.new_build_filename(paths.destination, paths.prefix, paths.data, resource.resource);
            return file.query_exists() ? file.get_path() : null;
        }

        private string? locate_opt(ResourceRef resource) {
            var file = File.new_build_filename(paths.destination, "opt", resource.resource);
            return file.query_exists() ? file.get_path() : null;
        }

        private string? locate_cfg(ResourceRef resource) {
            var file = File.new_build_filename(paths.destination, paths.sys_config, resource.resource);
            return file.query_exists() ? file.get_path() : null;
        }

        private string? locate_libres(ResourceRef resource) {
            var search = new string[] { "/usr/lib", "/usr/lib64", "/lib", "/lib64" };
            foreach (var path in search) {
                var file = File.new_build_filename(paths.destination, path, resource.resource);
                if(file.query_exists()) {
                    return file.get_path();
                }
            }
            return null;
        }

        private string? locate_canonlibres(ResourceRef resource) {
            var search = new string[] { "/usr/lib", "/lib" };
            foreach (var path in search) {
                var file = File.new_build_filename(paths.destination, path, resource.resource);
                if(file.query_exists()) {
                    return file.get_path();
                }
            }
            return null;
        }

        private string? locate_gio(ResourceRef resource) {
            var search = Iterate.these("/usr/lib64/gio/modules", "/usr/lib/gio/modules");
            // Debian-style multiarch keeps GIO modules in
            // /usr/lib/<triple>/gio/modules, which no fixed path covers:
            // enumerate whatever multiarch directories exist
            try {
                foreach(var entry in Iterate.directory("/usr/lib")) {
                    if(entry.contains("-linux-")) {
                        search = search.concat(Wrap.array(new string[] { @"/usr/lib/$entry/gio/modules" }));
                    }
                }
            }
            catch(FileError e) {
            }
            foreach (var path in search) {
                var file = File.new_build_filename(paths.destination, path, resource.resource);
                if(file.query_exists()) {
                    return file.get_path();
                }
            }
            return null;
        }

        private string? locate_app(ResourceRef resource) {
            var file = File.new_build_filename("/usr/share/applications", resource.resource);
            return file.query_exists() ? file.get_path() : null;
        }

        private string? locate_inc(ResourceRef resource) {
            var file = File.new_build_filename("/usr/include", resource.resource);
            return file.query_exists() ? file.get_path() : null;
        }

        private string? locate_sbin(ResourceRef resource) {
            var search = new string[] { "/usr/sbin", "/sbin" };
            foreach (var path in search) {
                var file = File.new_build_filename(paths.destination, path, resource.resource);
                if(file.query_exists()) {
                    return file.get_path();
                }
            }
            return null;
        }

        private string? locate_libexec(ResourceRef resource) {
            var file = File.new_build_filename("/usr/libexec", resource.resource);
            return file.query_exists() ? file.get_path() : null;
        }

        private string? locate_info(ResourceRef resource) {
            var file = File.new_build_filename("/usr/share/info", resource.resource);
            return file.query_exists() ? file.get_path() : null;
        }

        private string? locate_man(ResourceRef resource) {
            var file = File.new_build_filename("/usr/share/man", resource.resource);
            return file.query_exists() ? file.get_path() : null;
        }

        private string? locate_locale(ResourceRef resource) {
            var file = File.new_build_filename("/usr/share/locale", resource.resource);
            return file.query_exists() ? file.get_path() : null;
        }

        private string? locate_vapi(ResourceRef resource) {
            var search = new string[] { "/usr/share/vala/vapi", "/usr/share/vala-0.56/vapi" };
            foreach (var path in search) {
                var file = File.new_build_filename(paths.destination, path, resource.resource);
                if(file.query_exists()) {
                    return file.get_path();
                }
            }
            return null;
        }

        private string? locate_pc(ResourceRef resource) {
            var search = Iterate.these("/usr/lib/pkgconfig", "/usr/lib64/pkgconfig", "/usr/share/pkgconfig");
            // Debian-style multiarch keeps pkg-config files in
            // /usr/lib/<triple>/pkgconfig, which no fixed path covers:
            // enumerate whatever multiarch directories exist
            try {
                foreach(var entry in Iterate.directory("/usr/lib")) {
                    if(entry.contains("-linux-")) {
                        search = search.concat(Wrap.array(new string[] { @"/usr/lib/$entry/pkgconfig" }));
                    }
                }
            }
            catch(FileError e) {
            }
            var env = Environment.get_variable("PKG_CONFIG_PATH");
            if(env != null) {
                search = search.concat(Wrap.array(env.split(":")));
            }

            foreach (var path in search) {
                var file = File.new_build_filename(paths.destination, path, resource.resource);
                if(file.query_exists()) {
                    return file.get_path();
                }
            }
            return null;
        }

        private string? locate_gir(ResourceRef resource) {
            var file = File.new_build_filename("/usr/share/gir", resource.resource);
            return file.query_exists() ? file.get_path() : null;
        }

        private string? locate_typelib(ResourceRef resource) {
            var search = new string[] { "/usr/lib64/girepository-1.0", "/usr/lib/girepository-1.0", "/lib64/girepository-1.0", "/lib/girepository-1.0"  };
            foreach (var path in search) {
                var file = File.new_build_filename(paths.destination, path, resource.resource);
                if(file.query_exists()) {
                    return file.get_path();
                }
            }
            return null;
        }
    }

}