flowchart TD
    accTitle: Single Series Forecast Workflow
    accDescr: Step-by-step workflow for forecasting a single time series with system checking.

    check["1. Run check_system.py"] --> load["2. Load model
from_pretrained()"]
    load --> compile["3. Compile with ForecastConfig"]
    compile --> prep["4. Prepare data
pd.read_csv → np.array"]
    prep --> forecast["5. model.forecast()
horizon=N"]
    forecast --> extract["6. Extract point + PI"]
    extract --> plot["7. Plot or export results"]

    classDef step fill:#f3f4f6,stroke:#6b7280,stroke-width:2px,color:#1f2937
    class check,load,compile,prep,forecast,extract,plot step

import torch, numpy as np, pandas as pd, timesfm

# 1. System check (run once)
# python scripts/check_system.py

# 2-3. Load and compile
torch.set_float32_matmul_precision("high")
model = timesfm.TimesFM_2p5_200M_torch.from_pretrained(
    "google/timesfm-2.5-200m-pytorch"
)
model.compile(timesfm.ForecastConfig(
    max_context=512, max_horizon=52, normalize_inputs=True,
    use_continuous_quantile_head=True, fix_quantile_crossing=True,
))

# 4. Prepare data
df = pd.read_csv("weekly_demand.csv", parse_dates=["week"])
values = df["demand"].values.astype(np.float32)

# 5. Forecast
point, quantiles = model.forecast(horizon=52, inputs=[values])

# 6. Extract prediction intervals
forecast_df = pd.DataFrame({
    "forecast": point[0],
    "lower_80": quantiles[0, :, 1],
    "upper_80": quantiles[0, :, 9],
})

# 7. Plot
import matplotlib.pyplot as plt
fig, ax = plt.subplots(figsize=(12, 5))
ax.plot(values[-104:], label="Historical")
x_fc = range(len(values[-104:]), len(values[-104:]) + 52)
ax.plot(x_fc, forecast_df["forecast"], label="Forecast", color="tab:orange")
ax.fill_between(x_fc, forecast_df["lower_80"], forecast_df["upper_80"],
                alpha=0.2, color="tab:orange", label="80% PI")
ax.legend()
ax.set_title("52-Week Demand Forecast")
plt.tight_layout()
plt.savefig("forecast.png", dpi=150)
print("Saved forecast.png")

import pandas as pd, numpy as np

# Load wide-format CSV (one column per series)
df = pd.read_csv("all_stores.csv", parse_dates=["date"], index_col="date")
inputs = [df[col].dropna().values.astype(np.float32) for col in df.columns]

# Forecast all series at once (batched internally)
point, quantiles = model.forecast(horizon=30, inputs=inputs)

# Collect results
results = {}
for i, col in enumerate(df.columns):
    results[col] = {
        "forecast": point[i].tolist(),
        "lower_80": quantiles[i, :, 1].tolist(),
        "upper_80": quantiles[i, :, 9].tolist(),
    }

# Export
import json
with open("batch_forecasts.json", "w") as f:
    json.dump(results, f, indent=2)
print(f"Forecasted {len(results)} series → batch_forecasts.json")

import numpy as np

# Hold out the last H points for evaluation
H = 24
train = values[:-H]
actual = values[-H:]

point, quantiles = model.forecast(horizon=H, inputs=[train])
pred = point[0]

# Metrics
mae = np.mean(np.abs(actual - pred))
rmse = np.sqrt(np.mean((actual - pred) ** 2))
mape = np.mean(np.abs((actual - pred) / actual)) * 100

# Prediction interval coverage
lower = quantiles[0, :, 1]
upper = quantiles[0, :, 9]
coverage = np.mean((actual >= lower) & (actual <= upper)) * 100

print(f"MAE:  {mae:.2f}")
print(f"RMSE: {rmse:.2f}")
print(f"MAPE: {mape:.1f}%")
print(f"80% PI Coverage: {coverage:.1f}% (target: 80%)")