from typing import Dict, List, Optional, Tuple

import numpy as np
import torch
import torch.nn as nn
import torch.nn.functional as F
from torch.utils.data import DataLoader
import gradio as gr

from config import (
    DEVICE, NUM_CHANNELS, NUM_CLASSES, DEFAULT_PATCH_SIZE,
    BAND_NAMES, BAND_DESCRIPTIONS, CLASS_NAMES, IGNORE_INDEX,
    COMPOSITE_PRESETS, MAX_EXPERIMENTS,
)
from data import MultiSpectralDataset, load_data
from model import SmallUNet
from baseline import run_knn_baseline
from visualize import (
    render_composite, render_single_band,
    add_labels_overlay, multispectral_to_rgb,
    mask_to_color, overlay_mask, correctness_overlay,
    render_full_prediction_overlay,
    render_spectral_signatures_chart, render_index_map,
    _blank_rgb,
)
from metrics import compute_metrics, metrics_markdown


# ── Inference ────────────────────────────────────────────────

def build_prediction_cache(
    model: nn.Module, images: np.ndarray, batch_size: int = 8
) -> Tuple[np.ndarray, np.ndarray]:
    dummy = np.zeros((len(images), images.shape[-2], images.shape[-1]), dtype=np.int64)
    ds     = MultiSpectralDataset(images, dummy)
    loader = DataLoader(ds, batch_size=batch_size, shuffle=False)
    preds, probs = [], []
    model.eval()
    with torch.no_grad():
        for xb, _ in loader:
            xb = xb.to(DEVICE)
            pb = F.softmax(model(xb), dim=1)
            preds.append(torch.argmax(pb, dim=1).cpu().numpy())
            probs.append(pb.cpu().numpy())
    return np.concatenate(preds, axis=0), np.concatenate(probs, axis=0)


# ── Shared render helpers ────────────────────────────────────

def _get_exp_by_name(experiments: List[Dict], name: Optional[str]) -> Optional[Dict]:
    if not name:
        return None
    return next((e for e in experiments if e["name"] == name), None)


def pixel_info_markdown(
    x: int, y: int,
    img7: np.ndarray, gt: np.ndarray,
    pred: Optional[np.ndarray] = None,
    probs: Optional[np.ndarray] = None,
) -> str:
    h, w = gt.shape
    x = int(np.clip(x, 0, w - 1))
    y = int(np.clip(y, 0, h - 1))

    gt_class = int(gt[y, x])
    gt_name  = CLASS_NAMES[gt_class] if gt_class != IGNORE_INDEX else "Non étiqueté"
    lines    = [f"**Pixel ({x}, {y})**", f"Vérité terrain : **{gt_name}**"]

    if pred is not None:
        pred_class = int(pred[y, x])
        lines.append(f"Prédiction : **{CLASS_NAMES[pred_class]}**")
        if gt_class != IGNORE_INDEX:
            lines.append(f"Correct : **{'Oui' if pred_class == gt_class else 'Non'}**")
        if probs is not None:
            top = np.argsort(probs[:, y, x])[::-1][:3]
            lines.append("Meilleures probabilités : " + ", ".join(
                f"{CLASS_NAMES[i]} {probs[i, y, x]*100:.1f}%" for i in top
            ))

    lines += ["", "**Valeurs de bande**"] + [
        f"{BAND_DESCRIPTIONS[b]}: **{float(img7[b, y, x]):.3f}**"
        for b in range(img7.shape[0])
    ]
    return "\n\n".join(lines)


def experiments_table_markdown(experiments: List[Dict]) -> str:
    if not experiments:
        return "Aucune expérience entraînée pour l'instant."
    lines = [
        "| # | Nom | Taux d'app. | Époques | Canaux | Préc. val | mIoU |",
        "|---|---|---:|---:|---:|---:|---:|",
    ]
    for i, e in enumerate(experiments):
        cfg = e["config"]
        lines.append(
            f"| {i+1} | {e['name']} | {cfg['learning_rate']:.4f} | {cfg['epochs']} "
            f"| {cfg['base_channels']} "
            f"| {e['global_metrics']['overall_acc']*100:.1f}% "
            f"| {e['global_metrics']['miou']*100:.1f}% |"
        )
    return "\n".join(lines)


# ── Step 1 render helpers ────────────────────────────────────

def _render_step1_image(dataset_state: Dict, composite_choice: str) -> np.ndarray:
    full = dataset_state["full_image"]
    if composite_choice in COMPOSITE_PRESETS:
        r, g, b = COMPOSITE_PRESETS[composite_choice]
        base = render_composite(full, r, g, b)
    else:
        band_idx = BAND_DESCRIPTIONS.index(composite_choice)
        base = render_single_band(full, band_idx)
    return add_labels_overlay(base, dataset_state["full_train_mask"], dataset_state["full_val_mask"])


# ── Step 4 render helpers ────────────────────────────────────

def _render_step4_row(
    dataset_state: Dict,
    baseline_state: Optional[Dict],
    experiments: List[Dict],
    patch_idx: int,
) -> Tuple[np.ndarray, np.ndarray, np.ndarray, np.ndarray]:
    """Returns (rgb, gt_overlay, baseline_overlay, unet_overlay)."""
    val_images = dataset_state["val_images"]
    val_masks  = dataset_state["val_masks"]
    idx = max(0, min(patch_idx, len(val_images) - 1))

    rgb = multispectral_to_rgb(val_images[idx])
    gt  = val_masks[idx]
    gt_ov = overlay_mask(rgb, gt)

    if baseline_state is not None and idx < len(baseline_state["val_preds"]):
        bl_ov = overlay_mask(rgb, baseline_state["val_preds"][idx])
    else:
        bl_ov = _blank_rgb(*rgb.shape[:2])

    if experiments and idx < len(experiments[-1]["val_preds"]):
        un_ov = overlay_mask(rgb, experiments[-1]["val_preds"][idx])
    else:
        un_ov = _blank_rgb(*rgb.shape[:2])

    return rgb, gt_ov, bl_ov, un_ov


# ── Step 5 render helpers ────────────────────────────────────

def render_step5_panel(
    dataset_state: Dict,
    exp: Optional[Dict],
    patch_idx: int,
) -> Tuple[np.ndarray, np.ndarray, np.ndarray, str, np.ndarray]:
    """Returns (rgb, pred_color, overlay, metrics_md, error_map)."""
    blank = _blank_rgb()
    if dataset_state is None or exp is None:
        return blank, blank, blank, "Aucun modèle sélectionné.", blank

    val_images = dataset_state["val_images"]
    val_masks  = dataset_state["val_masks"]
    idx = max(0, min(patch_idx, len(val_images) - 1))
    rgb = multispectral_to_rgb(val_images[idx])
    gt  = val_masks[idx]

    if idx >= len(exp["val_preds"]):
        return rgb, mask_to_color(gt), overlay_mask(rgb, gt), "Données rechargées — réentraîner.", blank

    pred  = exp["val_preds"][idx].astype(np.int64)
    probs = exp["val_probs"][idx].astype(np.float32)
    m     = compute_metrics(pred, gt)
    return (
        rgb,
        mask_to_color(pred),
        overlay_mask(rgb, pred),
        metrics_markdown(m, title=f"{exp['name']} · patch {idx}"),
        correctness_overlay(rgb, pred, gt),
    )


# ── Gradio action functions ──────────────────────────────────

def load_dataset_action(patch_size: int):
    patch_size    = int(patch_size)
    dataset_state = load_data(patch_size)
    val_count     = len(dataset_state["val_images"])

    step1_img   = _render_step1_image(dataset_state, "H4 / H3 / H2")
    sig_chart   = render_spectral_signatures_chart(dataset_state["signatures"])
    ndvi_map    = render_index_map(
        dataset_state["ndvi"], "NDVI",
        dataset_state["full_train_mask"], dataset_state["full_val_mask"],
    )
    blank = _blank_rgb()

    dataset_info = "\n\n".join([
        "**Données chargées.**",
        dataset_state["status"],
        f"Bandes : {', '.join(BAND_NAMES)}  |  Classes : {', '.join(CLASS_NAMES)}",
        "**Carrés** = étiquettes d'entraînement · **Cercles** = étiquettes de validation",
    ])

    slider_upd = gr.update(maximum=max(0, val_count - 1), value=0)

    return (
        dataset_state,
        None,                               # baseline_state reset
        [],                                 # experiments_state reset
        # Tab 1
        dataset_info,
        step1_img,
        "Cliquez sur l'image pour inspecter un pixel.",
        # Tab 2
        sig_chart,
        ndvi_map,
        # Tab 3
        "Lancez la référence KNN après le chargement des données.",
        blank,
        # Tab 4
        "Entraînez un modèle à l'étape 4.",
        slider_upd,
        blank, blank, blank,
        # Tab 5
        "Aucune expérience pour l'instant.",
        gr.update(choices=[], value=None),
        gr.update(choices=[], value=None),
    )


def update_step1_composite(dataset_state, composite_choice: str):
    if dataset_state is None:
        return _blank_rgb(), "Chargez les données d'abord."
    img = _render_step1_image(dataset_state, composite_choice)
    return img, "Cliquez sur l'image pour inspecter un pixel."


def handle_click_step1(evt: gr.SelectData, dataset_state):
    if dataset_state is None:
        return "Chargez les données d'abord."
    x, y = evt.index
    full  = dataset_state["full_image"]
    fmask = dataset_state["full_val_mask"]
    H, W  = fmask.shape
    x, y  = int(np.clip(x, 0, W-1)), int(np.clip(y, 0, H-1))

    cls   = int(fmask[y, x])
    label = CLASS_NAMES[cls] if cls != IGNORE_INDEX else "Non étiqueté"
    lines = [
        f"**Pixel ({x}, {y})**  |  Étiquette val : **{label}**", "",
        "| Bande | Valeur |", "|---|---:|",
    ] + [f"| {BAND_DESCRIPTIONS[b]} | {float(full[b, y, x]):.4f} |" for b in range(7)]
    return "\n".join(lines)


def update_step2_index(dataset_state, index_choice: str):
    if dataset_state is None:
        return _blank_rgb()
    key = index_choice.lower()
    arr = dataset_state[key]
    return render_index_map(
        arr, index_choice,
        dataset_state["full_train_mask"], dataset_state["full_val_mask"],
    )


def run_baseline_action(dataset_state, k: int, progress=gr.Progress()):
    if dataset_state is None:
        raise gr.Error("Chargez les données d'abord.")
    progress(0.1, desc="KNN sur la scène complète...")
    k = int(k)
    full_pred, val_preds, metrics, metrics_md = run_knn_baseline(
        dataset_state["full_image"],
        dataset_state["full_train_mask"],
        dataset_state["full_val_mask"],
        dataset_state["val_images"],
        k=k,
    )
    progress(0.9, desc="Rendu en cours...")
    baseline_state = {
        "k":         k,
        "full_pred": full_pred,
        "val_preds": val_preds,
        "metrics":   metrics,
    }
    full_ov = render_full_prediction_overlay(
        dataset_state["full_image"], full_pred, dataset_state["full_val_mask"],
    )
    progress(1.0)
    return baseline_state, metrics_md, full_ov


def update_step4_patch(dataset_state, baseline_state, experiments, patch_idx: int):
    if dataset_state is None:
        blank = _blank_rgb()
        return blank, blank, blank  # no data loaded yet
    _, gt_ov, bl_ov, un_ov = _render_step4_row(
        dataset_state, baseline_state, experiments, int(patch_idx)
    )
    return gt_ov, bl_ov, un_ov


def train_experiment(
    dataset_state: Dict,
    baseline_state: Optional[Dict],
    experiments: List[Dict],
    learning_rate: float,
    batch_size: int,
    epochs: int,
    base_channels: int,
    run_name: str,
    progress=gr.Progress(),
):
    if dataset_state is None or "train_images" not in dataset_state:
        raise gr.Error("Chargez les données d'abord.")
    if len(experiments) >= MAX_EXPERIMENTS:
        raise gr.Error(
            f"Maximum de {MAX_EXPERIMENTS} expériences atteint. "
            "Comparez à l'étape 5, puis rechargez les données pour recommencer."
        )

    loader = DataLoader(
        MultiSpectralDataset(dataset_state["train_images"], dataset_state["train_masks"]),
        batch_size=int(batch_size), shuffle=True,
    )
    model     = SmallUNet(NUM_CHANNELS, NUM_CLASSES, int(base_channels)).to(DEVICE)
    optimizer = torch.optim.Adam(model.parameters(), lr=float(learning_rate))
    criterion = nn.CrossEntropyLoss(ignore_index=IGNORE_INDEX)

    n_epochs = int(epochs)
    history  = []
    for ep in range(n_epochs):
        progress(ep / n_epochs, desc=f"Epoch {ep+1}/{n_epochs}")
        model.train()
        total, n = 0.0, 0
        for xb, yb in loader:
            xb, yb = xb.to(DEVICE), yb.to(DEVICE)
            optimizer.zero_grad(set_to_none=True)
            loss = criterion(model(xb), yb)
            loss.backward()
            optimizer.step()
            total += float(loss.item())
            n += 1
        history.append(total / max(1, n))

    progress(0.95, desc="Inférence de validation...")
    val_preds, val_probs = build_prediction_cache(
        model, dataset_state["val_images"], batch_size=max(1, int(batch_size))
    )
    global_metrics = compute_metrics(
        val_preds.reshape(-1), dataset_state["val_masks"].reshape(-1)
    )
    progress(1.0)

    base = (run_name or f"Run {len(experiments)+1}").strip()
    existing = {e["name"] for e in experiments}
    name, ctr = base, 2
    while name in existing:
        name = f"{base} ({ctr})"
        ctr += 1

    experiment = {
        "name":               name,
        "config":             {
            "learning_rate": float(learning_rate),
            "batch_size":    int(batch_size),
            "epochs":        int(epochs),
            "base_channels": int(base_channels),
        },
        "train_loss_history": history,
        "global_metrics":     global_metrics,
        "val_preds":          val_preds.astype(np.int64),
        "val_probs":          val_probs.astype(np.float32),
    }
    experiments = experiments + [experiment]

    summary = "\n\n".join([
        f"**Entraînement terminé — {name}**",
        f"Appareil : **{DEVICE}** | Époques : **{n_epochs}** | Perte finale : **{history[-1]:.4f}**",
        f"Précision val : **{global_metrics['overall_acc']*100:.2f}%** (pixels étiquetés seulement)",
        f"mIoU val : **{global_metrics['miou']*100:.2f}%**",
    ])

    choices   = [e["name"] for e in experiments]
    val_count = len(dataset_state["val_images"])

    _, gt_ov, bl_ov, un_ov = _render_step4_row(dataset_state, baseline_state, experiments, 0)

    return (
        experiments,
        summary,
        gr.update(maximum=max(0, val_count-1), value=0),   # step4 patch slider
        gt_ov, bl_ov, un_ov,
        experiments_table_markdown(experiments),            # step5 table
        gr.update(choices=choices, value=None),             # step5 sel_a
        gr.update(choices=choices, value=None),             # step5 sel_b
    )


def update_step5_comparison(
    dataset_state, experiments, sel_a, sel_b, patch_idx: int
):
    idx  = int(patch_idx)
    exp_a = _get_exp_by_name(experiments, sel_a)
    exp_b = _get_exp_by_name(experiments, sel_b)
    a_outs = render_step5_panel(dataset_state, exp_a, idx)
    b_outs = render_step5_panel(dataset_state, exp_b, idx)
    return (*a_outs, *b_outs)


def handle_click_step5(
    evt: gr.SelectData,
    dataset_state, experiments, model_name, patch_idx: int,
) -> str:
    try:
        if dataset_state is None:
            return "Aucune donnée chargée."
        idx = max(0, min(int(patch_idx), len(dataset_state["val_images"])-1))
        exp = _get_exp_by_name(experiments, model_name)
        x, y = evt.index
        img7 = dataset_state["val_images"][idx]
        gt   = dataset_state["val_masks"][idx]
        pred  = exp["val_preds"][idx] if (exp and idx < len(exp["val_preds"])) else None
        probs = exp["val_probs"][idx] if (exp and idx < len(exp["val_probs"])) else None
        return pixel_info_markdown(int(x), int(y), img7, gt, pred, probs)
    except Exception as e:
        return f"Click error: `{e}`"