diff --git a/projects/gui/pylash/pylash/main.py b/projects/gui/pylash/pylash/main.py
new file mode 100644
index 0000000..116da14
--- /dev/null
+++ b/projects/gui/pylash/pylash/main.py
@@ -0,0 +1,253 @@
+import dataclasses
+import logging
+import pathlib
+import shutil
+import sys
+import textwrap
+from pprint import pformat
+from typing import Optional
+
+from PySide6.QtCore import Slot
+from PySide6.QtGui import QAction, QCloseEvent, QKeySequence, QPixmap
+from PySide6.QtWidgets import (
+    QApplication,
+    QGraphicsScene,
+    QGraphicsView,
+    QHBoxLayout,
+    QMessageBox,
+    QPushButton,
+    QStatusBar,
+    QVBoxLayout,
+    QWidget,
+)
+
+from pylash import settings, unsplash  # isort: skip
+
+# -------------
+# Prerequisites
+# -------------
+
+logging.basicConfig(
+    level=settings.DEBUG or logging.INFO,
+    format=settings.LOG_FORMAT,
+    style="{",
+)
+LOG = logging.getLogger("pylash.main")
+SECOND = 1000
+
+
+@dataclasses.dataclass()
+class Geometry:
+    x: int
+    y: int
+    width: int
+    height: int
+
+
+# -----------
+# Application
+# -----------
+
+
+class PylashWallpaperApp(QWidget):
+
+    STORE_DIR = pathlib.Path("~/Desktop/pylash").expanduser()
+
+    def __init__(self, client: unsplash.UnsplashClient, title: str = "") -> None:
+        super().__init__()
+        self.client = client
+        self.ctx = {}
+        self._current_image: Optional[pathlib.Path] = None
+
+        self.setup(title=title)
+
+    def setup(self, title: str):
+        self.setWindowTitle(title)
+        self.addAction(self._make_close_action(callback=self.close))
+        self._viewer = self._make_viewer(name="viewer", geom=(30, 30, 960, 480))
+        self._nextButton = self._make_button(
+            name="nextButton",
+            text="下一张",
+            geom=(50, 520, 400, 100),
+            callback=self.next,
+        )
+
+        self._saveButton = self._make_button(
+            name="saveButton",
+            text="保存",
+            geom=(550, 520, 400, 100),
+            callback=self.save,
+        )
+
+        self._status = self._make_status_bar()
+        # main window layout
+        layout = self._make_layout()
+        self.setLayout(layout)
+
+    def _make_status_bar(self, css: str = ""):
+        bar = QStatusBar()
+        style = """
+        background-color: none;
+        color: 'grey';
+        padding: 0;
+        border: none;
+        """
+
+        if css:
+            style = css
+            bar.setStyleSheet(style)
+        else:
+            bar.setStyleSheet(style)
+
+        ctx = self.ctx.setdefault("statusBar", {})
+        ctx.update(css=textwrap.dedent(style))
+
+        return bar
+
+    def _make_viewer(self, name: str, geom):
+        viewer = QGraphicsView()
+        viewer.setObjectName(name)
+        viewer.setGeometry(*geom)
+
+        ctx = self.ctx.setdefault("viewer", {})
+        ctx[name] = dict(name=name, geom=Geometry(*geom))
+        return viewer
+
+    def _make_button(self, name: str, text: str, geom, callback=None):
+        btn = QPushButton(text=text)
+        btn.setObjectName(name)
+        btn.setGeometry(*geom)
+
+        if callback:
+            btn.clicked.connect(callback)  # noqa: ignore
+
+        ctx = self.ctx.setdefault("button", {})
+        ctx[name] = dict(
+            name=name,
+            text=text,
+            geom=Geometry(*geom),
+            callback=callback.__name__ if callback else None,
+        )
+        return btn
+
+    def _make_layout(self):
+        layout = QVBoxLayout()
+        layout.addWidget(self._viewer)
+
+        # button layout
+        btn_layout = QHBoxLayout()
+        btn_layout.addWidget(self._nextButton)
+        btn_layout.addWidget(self._saveButton)
+
+        layout.addWidget(self._status)
+        layout.addLayout(btn_layout)
+        return layout
+
+    def _check_store_dir(self):
+        if not self.STORE_DIR.exists():
+            LOG.debug(f"initialization the directory to save a photo: {self.STORE_DIR}")
+            self.STORE_DIR.mkdir()
+
+    def _make_image_layer(self, data):
+        image = QPixmap()
+        image.loadFromData(data)
+
+        scene = QGraphicsScene()
+        scene.addPixmap(image)
+
+        return scene
+
+    @Slot()
+    def save(self):
+        """save photo to specific directory."""
+        self._check_store_dir()  # create a directory or not before saving
+        if not self._current_image:
+            self._status.showMessage(
+                "There isn't any image on the screen", timeout=5 * SECOND
+            )
+            return
+
+        name = self._current_image.name
+        fpath = self.STORE_DIR.joinpath(name)
+        if fpath.exists():
+            self._status.showMessage(
+                f"this image has saved to {fpath}", timeout=5 * SECOND
+            )
+            LOG.warning(f"{fpath} image has existed.")
+            return
+
+        shutil.copy(self._current_image, fpath)
+        self._status.showMessage(f"save to {fpath}")
+
+    @Slot()
+    def next(self):
+        """fetch the next photo."""
+        if self._status.currentMessage():
+            self._status.clearMessage()
+
+        image = self.client.fetch()
+        if not image:
+            msg = "the api has been limited, please try it after next hour time."
+            self._status.showMessage(msg)
+            LOG.warning(msg)
+            return
+
+        self._current_image = image
+
+        scene = self._make_image_layer(data=image.read_bytes())
+        self._viewer.setScene(scene)
+
+    def _make_close_action(self, callback):
+        key = "&Close"
+        close = QAction(key, self)
+        close.setShortcut(QKeySequence.Close)
+        close.triggered.connect(callback)  # noqa: ignore
+
+        ctx = self.ctx.setdefault("actions", {})
+
+        ctx["close"] = dict(
+            key=key,
+            shortcut=str(QKeySequence.Close),
+            callback=callback.__name__ if callback else None,
+        )
+
+        return close
+
+    def _close_event(self, event: QCloseEvent):
+        ctx_msg = pformat(self.ctx, compact=True)
+        LOG.debug(f"context: \n{ctx_msg}")
+        box = QMessageBox()
+        box.setIcon(QMessageBox.Question)
+        box.setWindowTitle("Quit")
+        box.setText("Are you sure to close window?")
+        box.setStandardButtons(QMessageBox.No | QMessageBox.Yes)
+        box.setDefaultButton(QMessageBox.No)
+
+        choice = box.exec()
+        key = "No" if choice == 65536 else "Yes"
+        LOG.debug(f"choice info(choice={key}, number={choice})")
+        if choice == QMessageBox.No:
+            event.ignore()
+        else:
+            event.accept()
+
+    def closeEvent(self, event: QCloseEvent):
+        self._close_event(event)
+
+
+def main():
+    # create application window loop.
+    window = QApplication(sys.argv)
+
+    # show content.
+    client = unsplash.UnsplashClient(token=settings.TOKEN)
+    app = PylashWallpaperApp(client=client, title="Unsplash 随机壁纸获取器")
+    app.resize(1440, 900)
+    app.show()
+
+    # exit when application window closed.
+    sys.exit(window.exec())
+
+
+if __name__ == "__main__":
+    main()
diff --git a/projects/gui/pylash/pylash/settings.py b/projects/gui/pylash/pylash/settings.py
new file mode 100644
index 0000000..efd4aca
--- /dev/null
+++ b/projects/gui/pylash/pylash/settings.py
@@ -0,0 +1,11 @@
+import os
+
+from dotenv import load_dotenv
+
+load_dotenv()
+
+
+DEBUG = 10 if os.getenv("PYLASH_DEBUG") else False
+TOKEN = os.getenv("PYLASH_TOKEN")
+
+LOG_FORMAT = "[{asctime}] [{levelname}] [{name}] [{funcName}:{lineno}] - {message}"
diff --git a/projects/gui/pylash/pylash/unsplash.py b/projects/gui/pylash/pylash/unsplash.py
new file mode 100644
index 0000000..41bf3ef
--- /dev/null
+++ b/projects/gui/pylash/pylash/unsplash.py
@@ -0,0 +1,98 @@
+import logging
+import pathlib
+import tempfile
+from typing import Optional
+from urllib.parse import parse_qs, urlparse
+
+import requests
+
+__all__ = "UnsplashClient"
+
+# --------------
+# Prerequisites
+# --------------
+
+API = "https://api.unsplash.com/photos/random"
+LOG = logging.getLogger(__name__)
+CACHED = pathlib.Path(tempfile.mkdtemp(prefix="pylash-"))
+
+
+class APIQueryException(Exception):
+    def __init__(self, status_code: int, detail) -> None:
+        self.status_code = status_code
+        self.detail = detail
+
+    def __str__(self) -> str:
+        return f"staus_code={self.status_code}, detail={self.detail}"
+
+
+# ---------------------
+# Unsplash Integration
+# ---------------------
+
+
+class UnsplashClient(object):
+    def __init__(self, token: str) -> None:
+        if not token:
+            raise ValueError(f"UnsplashClient need a token for initialization.")
+        self.token = token
+        self._remaining = 50
+        self._headers = {
+            "Accept-Version": "v1",
+            "Authorization": f"Client-ID {self.token}",
+        }
+
+    @property
+    def remaining(self) -> int:
+        return self._remaining
+
+    def _download(self, url: str) -> pathlib.Path:
+        """download image from target url"""
+
+        # extract name from url query string.
+        parser = urlparse(url)
+        params = parse_qs(parser.query)
+
+        name = params['ixid'][0]
+        file = CACHED.joinpath(f"{name}.jpg")
+        LOG.debug(f"save image to cached dir in: {file}")
+
+        response = requests.get(url, stream=True, params=dict(w=1080, fm="jpg", q=80))
+        total = 0
+        with open(file, mode="wb") as f:
+            for chunk in response.iter_content(1024):
+                total += f.write(chunk)
+
+        LOG.debug(f"writing data: {total >> 10} KB.")
+
+        return file
+
+    def fetch(self) -> Optional[pathlib.Path]:
+        if self._remaining == 0:
+            LOG.warning(
+                "the API request/usage has exhausted."
+                "Please try it after next hour time."
+            )
+            return
+
+        response = requests.get(
+            API, headers=self._headers, params={"orientation": "landscape"}
+        )
+        data = response.json()
+
+        if response.status_code != 200:
+            raise APIQueryException(status_code=response.status_code, detail=data)
+
+        # this property is not thread safety.
+        self._remaining = int(response.headers.get("X-Ratelimit-Remaining"))
+
+        url = data["urls"].get("raw")
+        image = self._download(url=url)
+        return image
+
+
+if __name__ == "__main__":
+    from pylash import settings
+
+    client = UnsplashClient(token=settings.TOKEN)
+    client.fetch()
diff --git a/projects/gui/quickstart.py b/projects/gui/quickstart.py
new file mode 100644
index 0000000..9a0f4f9
--- /dev/null
+++ b/projects/gui/quickstart.py
@@ -0,0 +1,20 @@
+import sys
+
+from PySide6.QtWidgets import QApplication, QMessageBox
+
+
+def main():
+    app = QApplication()
+
+    box = QMessageBox()
+    box.setText("Do you attempt to close window?")
+
+    box.setStandardButtons(box.No | box.Yes)
+    box.setDefaultButton(box.Yes)
+    box.show()
+
+    sys.exit(app.exec())
+
+
+if __name__ == '__main__':
+    main()
diff --git a/projects/gui/signals.py b/projects/gui/signals.py
new file mode 100644
index 0000000..e441f82
--- /dev/null
+++ b/projects/gui/signals.py
@@ -0,0 +1,49 @@
+import sys
+
+from PySide6.QtCore import Slot
+from PySide6.QtWidgets import (
+    QApplication,
+    QPushButton,
+    QStatusBar,
+    QVBoxLayout,
+    QWidget,
+)
+
+
+class MyWidget(QWidget):
+
+    counter = 0
+
+    def __init__(self) -> None:
+        super().__init__()
+        self.resize(200, 100)
+
+        btn = QPushButton()
+        btn.setText("Click me")
+        btn.clicked.connect(self.count)
+        self.btn = btn
+
+        bar = QStatusBar()
+        self.bar = bar
+
+        layout = QVBoxLayout()
+        layout.addWidget(self.btn)
+        layout.addWidget(self.bar)
+        self.setLayout(layout)
+
+    @Slot()
+    def count(self):
+        self.counter += 1
+        self.bar.showMessage(f"you have clicked: {self.counter}")
+
+
+def main():
+    app = QApplication()
+    widget = MyWidget()
+    widget.show()
+
+    sys.exit(app.exec())
+
+
+if __name__ == '__main__':
+    main()
diff --git a/projects/gui/widget.py b/projects/gui/widget.py
new file mode 100644
index 0000000..1de7198
--- /dev/null
+++ b/projects/gui/widget.py
@@ -0,0 +1,53 @@
+import sys
+
+from PySide6.QtWidgets import QApplication, QLabel, QLineEdit, QVBoxLayout, QWidget
+
+
+class MyWidget(QWidget):
+    def __init__(self):
+        super().__init__()
+        self.resize(200, 200)
+
+        label = QLabel()
+        label.setText("Hello, World!")
+        label.setStyleSheet(
+            """
+            QLabel {
+                font-size: 20px;
+                text-align: center;
+                margin: auto 50%;
+                padding-bottom: 5px;
+            }
+            """
+        )
+        self.label = label
+
+        editor = QLineEdit()
+        editor.setPlaceholderText("input your name here.")
+        editor.textChanged.connect(self.echo)
+        self.editor = editor
+
+        layout = QVBoxLayout()
+        layout.addWidget(self.label)
+        layout.addWidget(self.editor)
+
+        self.setLayout(layout)
+
+    def echo(self, name: str = ""):
+        if name:
+            msg = f"Hello, {name}!"
+        else:
+            msg = f"Hello, world!"
+        self.label.setText(msg)
+
+
+def main():
+    app = QApplication()
+    widget = MyWidget()
+    widget.show()
+
+    sys.exit(app.exec())
+
+
+if __name__ == '__main__':
+    main()