"""
SCImago CSV loader — builds in-memory ISSN → journal dict at startup.
Used PRIVATELY for quartile lookup only. Never exposed as branded data source in UI.

Changes from v1.0:
- _norm_issn removed — uses utils.norm_issn
- sourceid now included in ISSN index entries (was missing — broke verify_links)
"""
import csv
import re
import os
from typing import Optional
from utils import norm_issn

_scimago_cache: dict = {}


def load_scimago(csv_path: str = None) -> dict:
    global _scimago_cache
    if _scimago_cache:
        return _scimago_cache
    if csv_path is None:
        csv_path = os.path.join(os.path.dirname(__file__), "scimagojr_2025.csv")
    index = {}
    try:
        with open(csv_path, encoding="latin-1", newline="") as f:
            reader = csv.DictReader(f, delimiter=",")
            for row in reader:
                issn_raw = row.get("Issn", "")
                issn_parts = re.split(r"[,;\s]+", issn_raw)
                entry = {
                    "title":      row.get("Title", "").strip(),
                    "rank":       row.get("Rank", "").strip(),
                    "quartile":   row.get("SJR Best Quartile", "").strip(),
                    "h_index":    row.get("H index", "").strip(),
                    "categories": row.get("Categories", "").strip(),
                    "areas":      row.get("Areas", "").strip(),
                    "publisher":  row.get("Publisher", "").strip(),
                    "open_access":row.get("Open Access", "No").strip(),
                    "country":    row.get("Country", "").strip(),
                    "sourceid":   row.get("Sourceid", "").strip(),  # FIX: was missing
                }
                for part in issn_parts:
                    normed = norm_issn(part)
                    if normed:
                        index[normed] = entry
        _scimago_cache = index
        print(f"[SCImago] Loaded {len(index):,} ISSN entries.")
    except Exception as e:
        print(f"[SCImago] Failed: {e}")
        _scimago_cache = {}
    return _scimago_cache


def lookup_any(issns: list) -> Optional[dict]:
    index = load_scimago()
    for issn in issns:
        normed = norm_issn(str(issn)) if issn else None
        if normed and normed in index:
            result = dict(index[normed])
            result["matched_issn"] = normed
            return result
    return None


# ── Subject search index (separate from ISSN index) ──────────────────────
_subject_cache: list = []


def load_subject_index(csv_path: str = None) -> list:
    """Load full journal list for subject browsing — separate from ISSN lookup."""
    global _subject_cache
    if _subject_cache:
        return _subject_cache
    if csv_path is None:
        csv_path = os.path.join(os.path.dirname(__file__), "scimagojr_2025.csv")
    rows = []
    seen_titles = set()
    try:
        with open(csv_path, encoding="latin-1", newline="") as f:
            reader = csv.DictReader(f, delimiter=",")
            for row in reader:
                title = row.get("Title", "").strip()
                if not title or title in seen_titles:
                    continue
                seen_titles.add(title)
                issn_raw = row.get("Issn", "")
                issn_parts = re.split(r"[,;\s]+", issn_raw)
                issns = [norm_issn(p) for p in issn_parts if norm_issn(p)]
                primary_issn = issns[0] if issns else None
                try:
                    h = int(row.get("H index", "0").strip() or 0)
                except Exception:
                    h = 0
                rows.append({
                    "title":      title,
                    "issn":       primary_issn,
                    "quartile":   row.get("SJR Best Quartile", "").strip(),
                    "h_index":    h,
                    "categories": row.get("Categories", "").strip().lower(),
                    "areas":      row.get("Areas", "").strip().lower(),
                    "publisher":  row.get("Publisher", "").strip(),
                    "open_access":row.get("Open Access", "No").strip(),
                    "country":    row.get("Country", "").strip(),
                    "rank":       row.get("Rank", "").strip(),
                    "sourceid":   row.get("Sourceid", "").strip(),
                })
        _subject_cache = rows
        print(f"[SCImago] Subject index loaded: {len(rows):,} unique journals.")
    except Exception as e:
        print(f"[SCImago] Subject index failed: {e}")
        _subject_cache = []
    return _subject_cache


def search_by_subject(category: str, area: str, top_n: int = 15) -> list:
    """
    Search journals by normalised category + area strings from GPT.
    Returns top_n sorted by h_index descending.
    Tries: exact category match -> partial category -> area match.
    """
    rows = load_subject_index()
    cat_lower  = category.lower().strip() if category else ""
    area_lower = area.lower().strip()     if area     else ""

    def score(r):
        cats  = r["categories"]
        areas = r["areas"]
        if cat_lower and cat_lower in cats:
            return 3
        if cat_lower:
            words = [w for w in cat_lower.split() if len(w) > 3]
            if any(w in cats for w in words):
                return 2
        if area_lower and area_lower in areas:
            return 1
        if area_lower:
            words = [w for w in area_lower.split() if len(w) > 3]
            if any(w in areas for w in words):
                return 1
        return 0

    scored  = [(score(r), r) for r in rows]
    matched = [(s, r) for s, r in scored if s > 0]

    if not matched:
        return []

    matched.sort(key=lambda x: (-x[0], -x[1]["h_index"]))
    return [r for _, r in matched[:top_n]]


def get_all_areas() -> list:
    """Return sorted unique area names for frontend hints."""
    rows = load_subject_index()
    areas = set()
    for r in rows:
        for a in r["areas"].split(";"):
            a = a.strip().title()
            if a:
                areas.add(a)
    return sorted(areas)