"""Read-only page recognition and route planning from the game page map."""
import json
from collections import deque
from pathlib import Path

from .engine import Matcher


class PageMap:
    def __init__(self, root):
        self.root = Path(root)
        self.data = json.loads((self.root / 'workflows/page_map.json').read_text(encoding='utf-8'))
        self.pages = {page['id']: page for page in self.data['pages']}
        self.matcher = Matcher(self.root / 'assets')

    def identify(self, frame, previous_page=None):
        candidates = []
        for page in self.pages.values():
            for variant in page.get('recognition', []):
                scores = [self.matcher.score(frame, spec) for spec in variant]
                if scores and all(score >= spec.get('threshold', .86)
                                  for score, spec in zip(scores, variant)):
                    candidates.append({'id': page['id'], 'name': page['name'],
                                       'kind': page['kind'], 'score': round(min(scores), 4)})
                    break
        # A specific matching tab supersedes its matching container. Preserve
        # ambiguity between unrelated pages, even if their templates overlap.
        def ancestors(page_id):
            seen = set()
            current = self.pages[page_id].get('parent')
            while current in self.pages and current not in seen:
                seen.add(current)
                current = self.pages[current].get('parent')
            return seen

        matched_parents = set().union(*(ancestors(item['id']) for item in candidates)) if candidates else set()
        specific = [item for item in candidates if item['id'] not in matched_parents]
        # Tabs inside an overlay retain the overlay's priority. The parent
        # of a generic reward still comes from history, never from its art.
        overlays = [item for item in specific if item['kind'] == 'overlay' or any(
            self.pages[parent]['kind'] == 'overlay' for parent in ancestors(item['id']))]
        active = overlays or specific
        # Shared popups may have identical pixels. Only a known navigation
        # origin can choose between them; absence of origin stays ambiguous.
        groups = {self.pages[item['id']].get('shared_visual_group') for item in active}
        if len(active) > 1 and len(groups) == 1 and None not in groups and previous_page in self.pages:
            contextual = [item for item in active if previous_page in ancestors(item['id'])]
            if len(contextual) == 1:
                active = contextual
        return {'status': 'identified' if len(active) == 1 else 'ambiguous' if active else 'unknown',
                'page': active[0] if len(active) == 1 else None, 'candidates': candidates}

    def route(self, start, target):
        """Plan verified navigation only; this method sends no input events."""
        if start not in self.pages or target not in self.pages:
            raise ValueError('未知页面 ID。')
        queue = deque([(start, [])])
        seen = {start}
        while queue:
            current, steps = queue.popleft()
            if current == target:
                return steps
            for edge in self.data['edges']:
                if edge['from'] != current or edge['status'] not in ('live_verified', 'workflow_verified'):
                    continue
                if edge['to'] in seen:
                    continue
                seen.add(edge['to'])
                queue.append((edge['to'], steps + [edge]))
        raise ValueError('没有已验证的导航路径；需要先补充页面与返回关系。')