"""Offline precomputation for the Pigeon Pea Pangenome Atlas."""

import json
import re
from collections import Counter, defaultdict

import numpy as np
import pandas as pd
from scipy.spatial.distance import pdist, squareform
from sklearn.cluster import KMeans
from sklearn.metrics import silhouette_score

from src.utils import logger, timer, parse_country


@timer
def compute_gene_frequency(pav: pd.DataFrame) -> pd.DataFrame:
    """
    Compute per-gene frequency and core class.
    Output columns: gene_id, freq_count, freq_pct, core_class
    """
    n_lines = pav.shape[1]
    freq_count = pav.sum(axis=1).astype(int)
    freq_pct = (freq_count / n_lines * 100).round(2)

    def classify(pct):
        if pct >= 95:
            return "core"
        elif pct >= 15:
            return "shell"
        return "cloud"

    core_class = freq_pct.map(classify)

    df = pd.DataFrame({
        "gene_id": pav.index,
        "freq_count": freq_count.values,
        "freq_pct": freq_pct.values,
        "core_class": core_class.values,
    })
    logger.info(f"Gene frequency: {(df['core_class']=='core').sum()} core, "
                f"{(df['core_class']=='shell').sum()} shell, "
                f"{(df['core_class']=='cloud').sum()} cloud")
    return df


@timer
def compute_line_stats(pav: pd.DataFrame) -> pd.DataFrame:
    """
    Compute per-line statistics.
    Output columns: line_id, country, genes_present_count, unique_genes_count
    """
    n_lines = pav.shape[1]
    records = []
    for line_id in pav.columns:
        presence = pav[line_id]
        genes_present = int(presence.sum())
        # Unique genes: present in this line but no others
        unique_mask = (pav.sum(axis=1) == 1) & (presence == 1)
        unique_count = int(unique_mask.sum())
        country = parse_country(line_id)
        records.append({
            "line_id": line_id,
            "country": country,
            "genes_present_count": genes_present,
            "unique_genes_count": unique_count,
        })
    df = pd.DataFrame(records)
    logger.info(f"Line stats computed for {len(df)} lines")
    return df


@timer
def compute_line_embedding(pav: pd.DataFrame) -> pd.DataFrame:
    """
    UMAP embedding + KMeans clustering of lines.
    Output columns: line_id, umap_x, umap_y, cluster_id
    """
    import umap

    # Transpose: rows = lines, columns = genes
    X = pav.T.values.astype(np.float32)
    line_ids = list(pav.columns)

    # UMAP
    reducer = umap.UMAP(n_components=2, metric="jaccard", n_neighbors=15,
                        min_dist=0.1, random_state=42)
    embedding = reducer.fit_transform(X)

    # KMeans clustering — pick k by silhouette
    best_k, best_score = 3, -1
    for k in range(3, min(9, len(line_ids))):
        km = KMeans(n_clusters=k, random_state=42, n_init=10)
        labels = km.fit_predict(embedding)
        score = silhouette_score(embedding, labels)
        if score > best_score:
            best_k, best_score = k, score
            best_labels = labels

    logger.info(f"UMAP + KMeans: best k={best_k}, silhouette={best_score:.3f}")

    df = pd.DataFrame({
        "line_id": line_ids,
        "umap_x": embedding[:, 0],
        "umap_y": embedding[:, 1],
        "cluster_id": best_labels,
    })
    return df


@timer
def compute_similarity_topk(pav: pd.DataFrame, k: int = 15) -> pd.DataFrame:
    """
    Pairwise Jaccard similarity, keep top-K neighbors per line.
    Output columns: line_id, neighbor_line_id, jaccard_score
    """
    X = pav.T.values.astype(np.float32)
    line_ids = list(pav.columns)
    n = len(line_ids)

    # Compute pairwise Jaccard distance, convert to similarity
    dist_vec = pdist(X, metric="jaccard")
    dist_mat = squareform(dist_vec)
    sim_mat = 1.0 - dist_mat

    records = []
    for i in range(n):
        scores = sim_mat[i].copy()
        scores[i] = -1  # exclude self
        top_idx = np.argsort(scores)[::-1][:k]
        for j in top_idx:
            records.append({
                "line_id": line_ids[i],
                "neighbor_line_id": line_ids[j],
                "jaccard_score": round(float(scores[j]), 4),
            })

    df = pd.DataFrame(records)
    logger.info(f"Similarity top-{k}: {len(df)} pairs")
    return df


@timer
def build_gff_gene_parquet(gff_genes: pd.DataFrame, output_path: str) -> None:
    """Save parsed GFF gene DataFrame to parquet."""
    gff_genes.to_parquet(output_path, index=False)
    logger.info(f"GFF gene index saved: {output_path}")


@timer
def build_protein_parquet(protein_df: pd.DataFrame, output_path: str) -> None:
    """Save protein index to parquet."""
    protein_df.to_parquet(output_path, index=False)
    logger.info(f"Protein index saved: {output_path}")


@timer
def save_contig_index(contig_index: dict, contig_mapping: dict, output_path: str) -> None:
    """Save contig index as JSON."""
    import json
    data = {}
    for contig_id, length in contig_index.items():
        gff_seqid = None
        for gff_id, fasta_id in contig_mapping.items():
            if fasta_id == contig_id:
                gff_seqid = gff_id
                break
        data[contig_id] = {
            "length": length,
            "gff_seqid": gff_seqid or contig_id,
            "fasta_header": contig_id,
        }
    with open(output_path, "w") as f:
        json.dump(data, f, indent=2)
    logger.info(f"Contig index saved: {output_path}")


@timer
def compute_hotspot_bins(gff_genes: pd.DataFrame, gene_freq: pd.DataFrame,
                         contig_index: dict, bin_size: int = 100_000) -> pd.DataFrame:
    """
    Bin genes along contigs and compute variability scores.
    Output columns: contig_id, bin_start, bin_end, total_genes, cloud_genes,
                    shell_genes, core_genes, mean_freq, variability_score
    """
    # Join gff with gene frequency
    merged = gff_genes.merge(gene_freq, on="gene_id", how="inner")
    merged["midpoint"] = (merged["start"] + merged["end"]) // 2

    records = []
    for contig_id in merged["contig_id"].unique():
        contig_genes = merged[merged["contig_id"] == contig_id]
        max_pos = contig_genes["end"].max()

        for bin_start in range(0, max_pos + bin_size, bin_size):
            bin_end = bin_start + bin_size
            in_bin = contig_genes[
                (contig_genes["midpoint"] >= bin_start) &
                (contig_genes["midpoint"] < bin_end)
            ]
            if len(in_bin) == 0:
                continue

            core_count = int((in_bin["core_class"] == "core").sum())
            shell_count = int((in_bin["core_class"] == "shell").sum())
            cloud_count = int((in_bin["core_class"] == "cloud").sum())
            mean_freq = float(in_bin["freq_pct"].mean())
            variability_score = cloud_count + 0.5 * shell_count

            records.append({
                "contig_id": contig_id,
                "bin_start": bin_start,
                "bin_end": bin_end,
                "total_genes": len(in_bin),
                "core_genes": core_count,
                "shell_genes": shell_count,
                "cloud_genes": cloud_count,
                "mean_freq": round(mean_freq, 2),
                "variability_score": round(variability_score, 2),
            })

    df = pd.DataFrame(records)
    logger.info(f"Hotspot bins computed: {len(df)} bins across {df['contig_id'].nunique()} contigs")
    return df


@timer
def compute_cluster_markers(pav: pd.DataFrame, embedding: pd.DataFrame,
                            top_n: int = 50) -> pd.DataFrame:
    """
    Find marker genes for each cluster.
    Output columns: cluster_id, gene_id, in_cluster_freq, out_cluster_freq, marker_score
    """
    clusters = embedding[["line_id", "cluster_id"]].copy()
    records = []

    for cid in sorted(clusters["cluster_id"].unique()):
        in_lines = set(clusters[clusters["cluster_id"] == cid]["line_id"])
        out_lines = set(clusters[clusters["cluster_id"] != cid]["line_id"])

        in_cols = [c for c in pav.columns if c in in_lines]
        out_cols = [c for c in pav.columns if c in out_lines]

        if not in_cols or not out_cols:
            continue

        in_freq = pav[in_cols].mean(axis=1)
        out_freq = pav[out_cols].mean(axis=1)
        marker_score = in_freq - out_freq

        top_genes = marker_score.nlargest(top_n)
        for gene_id, score in top_genes.items():
            records.append({
                "cluster_id": int(cid),
                "gene_id": gene_id,
                "in_cluster_freq": round(float(in_freq[gene_id]), 4),
                "out_cluster_freq": round(float(out_freq[gene_id]), 4),
                "marker_score": round(float(score), 4),
            })

    df = pd.DataFrame(records)
    logger.info(f"Cluster markers: {len(df)} total across {df['cluster_id'].nunique()} clusters")
    return df


# ---------------------------------------------------------------------------
# New precomputation functions for UI overhaul
# ---------------------------------------------------------------------------


@timer
def compute_line_embedding_3d(pav: pd.DataFrame,
                              embedding_2d: pd.DataFrame) -> pd.DataFrame:
    """
    3D UMAP embedding of lines, reusing cluster_id from the 2D embedding.
    Output columns: line_id, umap_x, umap_y, umap_z, cluster_id
    """
    import umap

    # Transpose: rows = lines, columns = genes
    X = pav.T.values.astype(np.float32)
    line_ids = list(pav.columns)

    # UMAP with 3 components
    reducer = umap.UMAP(n_components=3, metric="jaccard", n_neighbors=15,
                        min_dist=0.1, random_state=42)
    embedding = reducer.fit_transform(X)

    # Reuse cluster_id from 2D embedding
    cluster_map = dict(zip(embedding_2d["line_id"], embedding_2d["cluster_id"]))

    df = pd.DataFrame({
        "line_id": line_ids,
        "umap_x": embedding[:, 0],
        "umap_y": embedding[:, 1],
        "umap_z": embedding[:, 2],
        "cluster_id": [int(cluster_map.get(lid, -1)) for lid in line_ids],
    })
    logger.info(f"3D UMAP embedding computed for {len(df)} lines")
    return df


@timer
def build_sunburst_data(gene_freq: pd.DataFrame, output_path: str) -> None:
    """
    Build Plotly go.Sunburst hierarchy arrays and save as JSON.
    Structure: total -> core / shell / cloud
    """
    core_count = int((gene_freq["core_class"] == "core").sum())
    shell_count = int((gene_freq["core_class"] == "shell").sum())
    cloud_count = int((gene_freq["core_class"] == "cloud").sum())
    total_count = core_count + shell_count + cloud_count

    data = {
        "ids": ["total", "core", "shell", "cloud"],
        "labels": ["All Genes", "Core", "Shell", "Cloud"],
        "parents": ["", "total", "total", "total"],
        "values": [total_count, core_count, shell_count, cloud_count],
    }

    with open(output_path, "w") as f:
        json.dump(data, f, indent=2)
    logger.info(f"Sunburst hierarchy saved: {output_path} "
                f"(total={total_count}, core={core_count}, "
                f"shell={shell_count}, cloud={cloud_count})")


@timer
def build_polar_contig_layout(hotspots: pd.DataFrame,
                              contig_index: dict,
                              output_path: str,
                              top_n: int = 20) -> None:
    """
    Assign the top contigs (by gene count) angular sectors for a polar layout.
    Saves per-contig metadata and per-bin variability mapped to angular positions.
    """
    # Aggregate gene counts per contig from hotspot bins
    contig_gene_counts = (
        hotspots.groupby("contig_id")["total_genes"]
        .sum()
        .nlargest(top_n)
    )
    top_contigs = list(contig_gene_counts.index)

    # Sum total length of selected contigs (use contig_index if available)
    contig_lengths = {}
    for cid in top_contigs:
        contig_lengths[cid] = contig_index.get(cid, int(
            hotspots[hotspots["contig_id"] == cid]["bin_end"].max()))

    total_length = sum(contig_lengths.values())

    # Assign angular sectors proportional to contig length
    sectors = []
    theta_cursor = 0.0
    for cid in top_contigs:
        length = contig_lengths[cid]
        arc = (length / total_length) * 360.0 if total_length > 0 else 0
        theta_start = round(theta_cursor, 4)
        theta_end = round(theta_cursor + arc, 4)

        # Map bins for this contig to angular positions
        contig_bins = hotspots[hotspots["contig_id"] == cid].sort_values("bin_start")
        bins_mapped = []
        for _, row in contig_bins.iterrows():
            # Map bin midpoint position to angular position within the sector
            bin_mid = (row["bin_start"] + row["bin_end"]) / 2
            frac = bin_mid / length if length > 0 else 0
            theta_bin = theta_start + frac * arc
            bins_mapped.append({
                "theta": round(theta_bin, 4),
                "total_genes": int(row["total_genes"]),
                "variability_score": float(row["variability_score"]),
                "core_genes": int(row["core_genes"]),
                "shell_genes": int(row["shell_genes"]),
                "cloud_genes": int(row["cloud_genes"]),
            })

        sectors.append({
            "contig_id": cid,
            "theta_start": theta_start,
            "theta_end": theta_end,
            "total_genes": int(contig_gene_counts[cid]),
            "total_length": int(length),
            "bins": bins_mapped,
        })

        theta_cursor += arc

    with open(output_path, "w") as f:
        json.dump(sectors, f, indent=2)
    logger.info(f"Polar contig layout saved: {output_path} "
                f"({len(sectors)} contigs, 360-degree arc)")


@timer
def compute_radar_axes(protein_index: pd.DataFrame,
                       output_path: str,
                       top_n: int = 10) -> None:
    """
    Find the top amino acids across all proteins and compute global mean percentages.
    Parses composition_summary strings (e.g. 'L:9.8%, S:7.2%, A:6.5%, G:5.8%, V:5.5%').
    Saves: { "axes": [...], "global_mean": {aa: mean_pct, ...} }
    """
    # Parse all composition summaries to accumulate per-protein AA percentages
    aa_totals = defaultdict(list)  # aa -> list of pct values (one per protein)

    for comp_str in protein_index["composition_summary"]:
        if not comp_str or pd.isna(comp_str):
            continue
        # Parse tokens like "L:9.8%"
        for token in comp_str.split(","):
            token = token.strip()
            match = re.match(r"([A-Z]):(\d+\.?\d*)%", token)
            if match:
                aa = match.group(1)
                pct = float(match.group(2))
                aa_totals[aa].append(pct)

    # Compute mean percentage for each AA (proteins where AA was not in top-5
    # are treated as 0 for ranking, but we report only the mean when present)
    n_proteins = len(protein_index)
    aa_mean = {}
    for aa, pct_list in aa_totals.items():
        # Mean across ALL proteins (assume 0 for those where it wasn't in top-5)
        aa_mean[aa] = round(sum(pct_list) / n_proteins, 3)

    # Select top-N by global mean
    sorted_aas = sorted(aa_mean.items(), key=lambda x: -x[1])[:top_n]
    axes = [aa for aa, _ in sorted_aas]
    global_mean = {aa: pct for aa, pct in sorted_aas}

    data = {
        "axes": axes,
        "global_mean": global_mean,
    }

    with open(output_path, "w") as f:
        json.dump(data, f, indent=2)
    logger.info(f"Radar axes saved: {output_path} (top {top_n} AAs: {axes})")