"""
Flask web interface for the toroidal transformer designer + simulator.

Routes
------
GET  /                 → main page
POST /api/design       → run design_transformer(), return winding info + drawing PNG (base64)
POST /api/sweep        → run sweep_operating_points(), return JSON dataset
"""

import base64
import json
import math
import os
import tempfile

from flask import Flask, render_template, request, jsonify

from designer import ToroidCore, WindingSpec, WireSpec, design_transformer
from sim_toroid import (
    ToroidSimulator, SimConstraints,
    sweep_operating_points, SweepEntry,
)
from draw_toroid import draw_toroid

app = Flask(__name__)


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------

def _parse_core(data: dict) -> ToroidCore:
    """Build ToroidCore from request dict."""
    Ae = data.get("Ae_mm2")
    Ve = data.get("Ve_mm3")
    return ToroidCore(
        ID_mm=float(data["ID_mm"]),
        OD_mm=float(data["OD_mm"]),
        height_mm=float(data["height_mm"]),
        Ae_mm2=float(Ae) if Ae not in (None, "") else None,
        Ve_mm3=float(Ve) if Ve not in (None, "") else None,
        Pv_func=None,   # not editable in the UI; uses built-in fallback
    )


def _parse_windings(data: dict) -> list[WindingSpec]:
    """
    Parse winding list from request dict.

    Expected format:
      windings: [
        { name: "primary",   taps: [0, 25, 50],    awg: [22, 22] },
        { name: "secondary", taps: [0, 100, 50, 50, 50], awg: [22, 22, 22, 26] },
      ]
    """
    specs = []
    for w in data["windings"]:
        taps = [int(t) for t in w["taps"]]
        awg  = [int(a) for a in w["awg"]]
        specs.append(WindingSpec(awg=awg, taps=taps, name=str(w.get("name", "winding"))))
    return specs


def _actual_fill_factor(core: ToroidCore, results) -> float:
    """
    Compute actual fill factor = total wire cross-section area placed / window area.
    Sums wire area for every turn placed across all windings.
    """
    window_area = core.window_area_mm2
    if window_area <= 0:
        return 0.0
    total_wire_area = 0.0
    for wr in results:
        for seg in wr.segments:
            wire = WireSpec.from_awg(seg.awg)
            r = wire.diameter_mm / 2.0
            total_wire_area += math.pi * r * r * seg.turns
    return total_wire_area / window_area


def _drawing_b64(core: ToroidCore, results, actual_fill: float) -> str:
    """Render the toroid PNG and return it as a base64 data-URI string."""
    with tempfile.NamedTemporaryFile(suffix=".png", delete=False) as f:
        tmp_path = f.name
    try:
        draw_toroid(core, results, output_path=tmp_path, dpi=150, fig_size_mm=160,
                    actual_fill=actual_fill)
        with open(tmp_path, "rb") as f:
            png_bytes = f.read()
    finally:
        try:
            os.unlink(tmp_path)
        except OSError:
            pass
    return "data:image/png;base64," + base64.b64encode(png_bytes).decode()


def _winding_result_to_dict(wr) -> dict:
    """Serialise a WindingResult for JSON."""
    segs = []
    for seg in wr.segments:
        segs.append({
            "segment_index": seg.segment_index,
            "tap_number": seg.segment_index + 1,
            "awg": seg.awg,
            "turns": seg.turns,
            "wire_length_m": round(seg.wire_length_m, 4),
            "resistance_mohm": round(seg.resistance_ohm * 1000, 3),
            "weight_g": round(seg.weight_g, 3),
            "fits": seg.fits,
            "layers": [
                {
                    "layer_index": lr.layer_index,
                    "turns_capacity": lr.turns_capacity,
                    "turns_used": lr.turns_used,
                    "L_turn_mm": round(lr.L_turn_mm, 2),
                }
                for lr in seg.layers
            ],
        })
    return {
        "name": wr.spec.name,
        "total_turns": wr.spec.total_turns,
        "feasible": wr.feasible,
        "total_wire_length_m": round(wr.total_wire_length_m, 4),
        "total_resistance_mohm": round(wr.total_resistance_ohm * 1000, 3),
        "total_weight_g": round(wr.total_weight_g, 3),
        "segments": segs,
        "n_taps": len(wr.spec.taps) - 1,
    }


def _sweep_entry_to_dict(e: SweepEntry) -> dict:
    """Convert SweepEntry to a plain dict suitable for JSON."""
    d = e.as_dict()
    # Replace NaN (not JSON-serialisable) with None
    for k, v in d.items():
        if isinstance(v, float) and math.isnan(v):
            d[k] = None
    return d


# ---------------------------------------------------------------------------
# Routes
# ---------------------------------------------------------------------------

@app.route("/")
def index():
    return render_template("index.html")


@app.route("/api/design", methods=["POST"])
def api_design():
    """
    Run design_transformer() and return winding info + PNG drawing.

    Request body (JSON):
    {
      "ID_mm": 21.5,  "OD_mm": 46.5,  "height_mm": 22.8,
      "Ae_mm2": 142.5,   // optional
      "Ve_mm3": 15219,   // optional
      "fill_factor": 0.35,
      "windings": [
        { "name": "primary",   "taps": [0, 25, 50],         "awg": [22, 22] },
        { "name": "secondary", "taps": [0, 100, 50, 50, 50],"awg": [22, 22, 22, 26] }
      ]
    }
    """
    try:
        data = request.get_json(force=True)
        core = _parse_core(data)
        specs = _parse_windings(data)
        fill_factor = float(data.get("fill_factor", 0.35))

        results = design_transformer(core, specs, fill_factor=fill_factor)

        actual_fill = _actual_fill_factor(core, results)
        drawing_b64 = _drawing_b64(core, results, actual_fill)
        windings_info = [_winding_result_to_dict(wr) for wr in results]

        # Thermal surface area of wound toroid (m²):
        # outer cylinder + top/bottom annular faces + inner bore cylinder
        OD_m = core.OD_mm * 1e-3
        ID_m = core.ID_mm * 1e-3
        H_m  = core.height_mm * 1e-3
        A_outer  = math.pi * OD_m * H_m
        A_faces  = 2 * math.pi / 4 * (OD_m**2 - ID_m**2)
        A_bore   = math.pi * ID_m * H_m
        A_surface_m2 = A_outer + A_faces + A_bore

        return jsonify({
            "success": True,
            "windings": windings_info,
            "drawing": drawing_b64,
            "fill_factor_target": fill_factor,
            "fill_factor_actual": round(actual_fill, 4),
            "window_area_mm2": round(core.window_area_mm2, 2),
            "A_surface_m2": round(A_surface_m2, 6),
        })

    except Exception as exc:
        return jsonify({"success": False, "error": str(exc)}), 400


@app.route("/api/sweep", methods=["POST"])
def api_sweep():
    """
    Run sweep_operating_points() over a grid of frequencies × loads.

    Request body (JSON):
    {
      // Same core + windings as /api/design ...
      "fill_factor": 0.35,
      "frequencies": [256, 870, 3140],
      "loads": [[10, 0], [50, 0], [100, 0]],   // [R, X] pairs
      "target_power_W": 25.0,
      "Vp_min": 1.0,
      "Vp_max": 50.0,
      "Vp_steps": 100,
      "power_tol_pct": 2.0,
      "constraints": {
        "B_max_T": 0.3,
        "Vp_max": 50.0,
        "Vs_max": 120.0,
        "Ip_max": 3.0,
        "Is_max": 2.0,
        "P_out_max_W": 100.0
      }
    }
    """
    try:
        data = request.get_json(force=True)
        core = _parse_core(data)
        specs = _parse_windings(data)
        fill_factor = float(data.get("fill_factor", 0.35))

        results = design_transformer(core, specs, fill_factor=fill_factor)

        # Expect exactly 2 windings: primary and secondary
        if len(results) < 2:
            return jsonify({"success": False, "error": "Need at least 2 windings"}), 400

        # Use first winding as primary, second as secondary
        primary_result = results[0]
        secondary_result = results[1]

        sim = ToroidSimulator(core=core, primary=primary_result, secondary=secondary_result)

        # Constraints
        cdata = data.get("constraints", {})
        constraints = SimConstraints(
            B_max_T=float(cdata.get("B_max_T", 0.3)),
            Vp_max=float(cdata.get("Vp_max", float("inf"))),
            Vs_max=float(cdata.get("Vs_max", float("inf"))),
            Ip_max=float(cdata.get("Ip_max", float("inf"))),
            Is_max=float(cdata.get("Is_max", float("inf"))),
            P_out_max_W=float(cdata.get("P_out_max_W", float("inf"))),
        )

        frequencies = [float(f) for f in data.get("frequencies", [256.0])]
        loads = [(float(p[0]), float(p[1])) for p in data.get("loads", [[10.0, 0.0]])]
        target_power_W = float(data.get("target_power_W", 10.0))
        Vp_min = float(data.get("Vp_min", 1.0))
        Vp_max_sweep = float(data.get("Vp_max", 50.0))
        Vp_steps = int(data.get("Vp_steps", 100))
        power_tol_pct = float(data.get("power_tol_pct", 2.0))

        entries = sweep_operating_points(
            sim=sim,
            frequencies=frequencies,
            loads=loads,
            target_power_W=target_power_W,
            constraints=constraints,
            Vp_min=Vp_min,
            Vp_max=Vp_max_sweep,
            Vp_steps=Vp_steps,
            power_tol_pct=power_tol_pct,
        )

        rows = [_sweep_entry_to_dict(e) for e in entries]

        return jsonify({
            "success": True,
            "rows": rows,
            "frequencies": frequencies,
            "loads": [[r, x] for r, x in loads],
        })

    except Exception as exc:
        import traceback
        return jsonify({"success": False, "error": str(exc),
                        "traceback": traceback.format_exc()}), 400


# ---------------------------------------------------------------------------
# Preset persistence
# ---------------------------------------------------------------------------

PRESETS_DIR = os.path.join(os.path.dirname(__file__), "presets")
os.makedirs(PRESETS_DIR, exist_ok=True)

# Valid preset categories
_PRESET_TYPES = {"core", "windings", "constraints", "sim"}


def _preset_path(ptype: str) -> str:
    return os.path.join(PRESETS_DIR, f"{ptype}.json")


def _load_store(ptype: str) -> dict:
    """Load the JSON store for a preset type; return {} on missing/corrupt."""
    path = _preset_path(ptype)
    if not os.path.exists(path):
        return {}
    try:
        with open(path, "r", encoding="utf-8") as f:
            return json.load(f)
    except Exception:
        return {}


def _save_store(ptype: str, store: dict) -> None:
    path = _preset_path(ptype)
    with open(path, "w", encoding="utf-8") as f:
        json.dump(store, f, indent=2)


@app.route("/api/presets/<ptype>", methods=["GET"])
def presets_list(ptype: str):
    """Return list of saved preset names and the last-used name."""
    if ptype not in _PRESET_TYPES:
        return jsonify({"success": False, "error": f"Unknown type '{ptype}'"}), 400
    store = _load_store(ptype)
    names = [k for k in store if not k.startswith("_")]
    last = store.get("_last", None)
    return jsonify({"success": True, "names": sorted(names), "last": last})


@app.route("/api/presets/<ptype>/<name>", methods=["GET"])
def presets_load(ptype: str, name: str):
    """Load a named preset and mark it as last-used."""
    if ptype not in _PRESET_TYPES:
        return jsonify({"success": False, "error": f"Unknown type '{ptype}'"}), 400
    store = _load_store(ptype)
    if name not in store:
        return jsonify({"success": False, "error": f"Preset '{name}' not found"}), 404
    store["_last"] = name
    _save_store(ptype, store)
    return jsonify({"success": True, "name": name, "data": store[name]})


@app.route("/api/presets/<ptype>/<name>", methods=["POST"])
def presets_save(ptype: str, name: str):
    """Save (create or overwrite) a named preset and mark it as last-used."""
    if ptype not in _PRESET_TYPES:
        return jsonify({"success": False, "error": f"Unknown type '{ptype}'"}), 400
    if not name or name.startswith("_"):
        return jsonify({"success": False, "error": "Invalid preset name"}), 400
    data = request.get_json(force=True)
    store = _load_store(ptype)
    store[name] = data
    store["_last"] = name
    _save_store(ptype, store)
    return jsonify({"success": True, "name": name})


@app.route("/api/presets/<ptype>/<name>", methods=["DELETE"])
def presets_delete(ptype: str, name: str):
    """Delete a named preset."""
    if ptype not in _PRESET_TYPES:
        return jsonify({"success": False, "error": f"Unknown type '{ptype}'"}), 400
    store = _load_store(ptype)
    if name not in store:
        return jsonify({"success": False, "error": f"Preset '{name}' not found"}), 404
    del store[name]
    if store.get("_last") == name:
        remaining = [k for k in store if not k.startswith("_")]
        store["_last"] = remaining[-1] if remaining else None
    _save_store(ptype, store)
    return jsonify({"success": True})


if __name__ == "__main__":
    app.run(debug=True, host="0.0.0.0", port=5000)