Merge pull request #9 from Redume/feat/support-typst

feat: Support for typst to create a graph

Author: Redume

chart/README.md

@@ -1,4 +1,4 @@
-This microservice generates graphs of currency exchange rates using Python and the `matplotlib` library. 
+This microservice generates graphs of currency exchange rates using Python and the `matplotlib` and `typst` library. 
 It retrieves historical exchange rate data from an internal database and visualizes the data in the form of line charts
 
 
@@ -11,4 +11,5 @@ It retrieves historical exchange rate data from an internal database and visuali
 - [encode/uvicorn](https://github.com/encode/uvicorn) — [BSD-3-Clause](https://github.com/encode/uvicorn/blob/master/LICENSE.md)
 - [fastapi/fastapi](https://github.com/fastapi/fastapi) — [MIT](https://github.com/fastapi/fastapi/blob/master/LICENSE)
 - [selwin/python-user-agents](https://github.com/selwin/python-user-agents) — [MIT](https://github.com/selwin/python-user-agents/blob/master/LICENSE.txt)
-- [MagicStack/asyncpg](https://github.com/MagicStack/asyncpg)—- [Apache-2.0](https://github.com/MagicStack/asyncpg/blob/master/LICENSE)
+- [MagicStack/asyncpg](https://github.com/MagicStack/asyncpg) — [Apache-2.0](https://github.com/MagicStack/asyncpg/blob/master/LICENSE)
+- [messense/typst-py](https://github.com/messense/typst-py/) — [Apache-2.0](https://github.com/messense/typst-py/blob/main/LICENSE)

chart/chart_backend/matplotlib.py

@@ -0,0 +1,98 @@
+"""
+Module for generating smoothed currency exchange rate charts.
+
+This module provides an asynchronous function to create a visual
+representation of historical currency exchange rates. The function
+uses spline interpolation to smooth data points and matplotlib
+to generate a JPEG chart image returned as a binary stream.
+
+It requires the Currency schema for input parameters and uses
+matplotlib and scipy for plotting and interpolation.
+"""
+
+from datetime import datetime
+from io import BytesIO
+from typing import Optional
+
+import numpy as np
+from database.server import Database
+from matplotlib import pyplot as plt
+from schemas.currency import Currency
+from scipy.interpolate import make_interp_spline
+from utils.config.get_dsn import get_dsn
+from utils.config.load_config import load_config
+
+config = load_config("config.hjson")
+
+
+async def create_chart(
+    currency: Currency, dates: list, rates: list
+) -> Optional[BytesIO]:
+    """
+    Generates a smoothed currency exchange rate chart image
+    from historical data.
+
+    This asynchronous function receives historical exchange rate data
+    for aspecified currency pair over a given date range.
+    It applies spline interpolation to smooth the rate curve,
+    then creates a matplotlib plot
+    with formatted date labels on the x-axis. The resulting plot is saved
+    as a JPEG image in a binary stream.
+
+    Args:
+        currency (Currency): An object containing details about
+            the currency pair and period.
+        dates (list): A list of datetime objects
+        representing the dates of the data points.
+        rates (list):  A list of float values representing
+            exchange rates corresponding to the dates.
+
+    Returns:
+        Optional[BytesIO]: A binary stream containing
+            the JPEG image of the chart,
+        or None if the interpolation fails or there is insufficient data.
+    """
+    x_values = np.arange(len(dates))
+    try:
+        spline = make_interp_spline(x_values, rates, k=2)
+    except ValueError:
+        return None
+
+    new_x = np.linspace(0, len(dates) - 1, 200)
+    new_y = spline(new_x)
+
+    fig, ax = plt.subplots(figsize=(15, 6))
+
+    ax.set_xticks(np.linspace(0, len(dates) - 1, 10))
+    current_year = datetime.now().year
+    ax.set_xticklabels(
+        [
+            (
+                dates[int(i)].strftime("%m-%d")
+                if dates[int(i)].year == current_year
+                else dates[int(i)].strftime("%Y-%m-%d")
+            )
+            for i in np.linspace(0, len(dates) - 1, 10).astype(int)
+        ],
+    )
+
+    ax.tick_params(axis="both", labelsize=10)
+
+    if rates[0] < rates[-1]:
+        color = "green"
+    elif rates[0] > rates[-1]:
+        color = "red"
+    else:
+        color = "grey"
+
+    ax.plot(new_x, new_y, color=color, linewidth=2)
+
+    ax.spines["top"].set_visible(False)
+    ax.spines["right"].set_visible(False)
+
+    buf = BytesIO()
+    fig.savefig(buf, format="jpeg", bbox_inches="tight")
+    plt.close(fig)
+    buf.seek(0)
+
+    return buf

chart/chart_backend/typst.py

@@ -0,0 +1,67 @@
+"""
+Module for generating currency exchange rate charts using Typst.
+
+This module provides an asynchronous function that creates a currency
+exchange rate chart based on historical data for a specified currency pair.
+It compiles the chart using the Typst template engine and returns the chart
+as a PNG image in a binary stream.
+
+The function expects a list of datetime objects for dates and corresponding
+exchange rates, along with currency details and display parameters.
+"""
+
+import json
+from datetime import datetime
+from io import BytesIO
+from typing import Optional
+
+import typst
+from database.server import Database
+from schemas.currency import Currency
+from utils.config.get_dsn import get_dsn
+from utils.config.load_config import load_config
+
+config = load_config("config.hjson")
+
+
+async def create_chart(
+    currency: Currency, dates: list, rates: list
+) -> Optional[BytesIO]:
+    """
+    Generates a currency exchange rate chart based on historical data.
+
+    This function takes historical currency exchange rate data
+        for a specified period,
+    prepares the data, and compiles a chart image using Typst.
+    It returns a binary stream containing the chart image in PNG format.
+
+    Args:
+        currency (Currency):
+            An object containing currency pair details and settings.
+        dates (list):
+            A list of datetime objects representing observation dates.
+        rates (list):
+            A list of exchange rate values corresponding to the dates.
+
+    Returns:
+        Optional[BytesIO]: A binary stream
+            with the generated PNG chart imageб
+            or None if no data is available
+            or an error occurs during generation.
+    """
+    dpi = 1
+
+    compiler = typst.Compiler(
+        "./typst_template/simple.typ",
+        sys_inputs={
+            "from_currency": currency.from_currency.upper(),
+            "conv_currency": currency.conv_currency.upper(),
+            "x": json.dumps([d.timestamp() for d in dates]),
+            "y": json.dumps(rates),
+            "dpi": str(dpi),
+            "width": str(currency.width),
+            "period": currency.period if currency.period is not None else "",
+        },
+    )
+
+    return BytesIO(compiler.compile(output=None, ppi=dpi, format="png"))