from fastapi import FastAPI, File, Form, HTTPException, Request, UploadFile
from fastapi.responses import RedirectResponse, StreamingResponse
from fastapi.staticfiles import StaticFiles

from dea.bode import calculate_bode_compare_response, calculate_bode_response
from dea.config import (
    BODE_MAX_MULTIPLIER,
    BODE_POINTS,
    MAX_COEFFICIENTS,
    MAX_CSV_BYTES,
    MAX_PLOT_POINTS,
    NYQUIST_MARGIN,
)
from dea.csv_processing import (
    downsample_for_plot,
    filter_preview_response,
    filtered_csv_data,
    filtered_csv_text,
    read_csv_upload,
)
from dea.filter_design import design_response
from dea.schemas import BodeCompareParams, BodeParams, DesignParams
from dea.security import (
    SECURITY_HEADERS,
    add_security_headers,
    is_lan_or_loopback,
    lan_denied_response,
)
from dea.validation import (
    normalize_coefficients,
    parse_coefficients,
    require_finite,
    validate_coefficients,
    validate_frequency,
)

app = FastAPI(title="Difference Equation Analyzer API")


@app.middleware("http")
async def restrict_to_lan(request: Request, call_next):
    client_ip = request.client.host if request.client else None
    if not is_lan_or_loopback(client_ip):
        return lan_denied_response()
    response = await call_next(request)
    return add_security_headers(response)


# 掛載靜態網頁檔案，將預設首頁導向到 /ui/
app.mount("/ui", StaticFiles(directory="static", html=True), name="static")


@app.get("/")
def redirect_to_ui():
    return RedirectResponse(url="/ui/")


@app.post("/api/design")
def design_filter(params: DesignParams):
    try:
        return design_response(params)
    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(status_code=400, detail=str(e))


@app.post("/api/bode")
def calculate_bode(params: BodeParams):
    try:
        return calculate_bode_response(params)
    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(status_code=400, detail=str(e))


@app.post("/api/bode/compare")
def calculate_bode_compare(params: BodeCompareParams):
    try:
        return calculate_bode_compare_response(params)
    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(status_code=400, detail=str(e))


@app.post("/api/filter")
async def filter_csv(
    file: UploadFile = File(...),
    b: str = Form(...),
    a: str = Form(...),
    col_idx: int = Form(0),
):
    try:
        b_vals = parse_coefficients(b, "b")
        a_vals = parse_coefficients(a, "a")
        df = await read_csv_upload(file)
        return filter_preview_response(df, b_vals, a_vals, col_idx)
    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(status_code=400, detail=f"CSV處理失敗: {str(e)}")


@app.post("/api/filter/download")
async def filter_csv_download(
    file: UploadFile = File(...),
    b: str = Form(...),
    a: str = Form(...),
    col_idx: int = Form(0),
):
    try:
        b_vals = parse_coefficients(b, "b")
        a_vals = parse_coefficients(a, "a")
        df = await read_csv_upload(file)
        csv_text = filtered_csv_text(df, b_vals, a_vals, col_idx)

        return StreamingResponse(
            iter([csv_text]),
            media_type="text/csv",
            headers={"Content-Disposition": "attachment; filename=filtered_output.csv"},
        )
    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(status_code=400, detail=f"CSV處理失敗: {str(e)}")