"""Reviewed publications. A generated digest is not one of these records."""
from datetime import datetime
from pathlib import Path

from .store import all_records, get, put

FIELDS = {'schema_version', 'title', 'reviewer', 'reviewed_at', 'claims', 'supersedes'}
CLAIM_FIELDS = {'statement', 'disposition', 'capture_id', 'exclusion_reason'}


def publish(root, value):
    root = Path(root)
    record = _record(root, value)
    ident = put(root, 'publications', record)
    _render(root, ident, record)
    return ident


def verify(root):
    root = Path(root)
    directory = root / 'data' / 'publications'
    if not directory.exists():
        return 0
    reviewed = (root / 'digests' / 'reviewed').resolve()
    count = 0
    for ident, record in all_records(root, 'publications'):
        _record(root, record, existing=ident)
        path = (reviewed / f'{ident}.md').resolve()
        if path.parent != reviewed or not path.is_file():
            raise ValueError(f'reviewed publication file missing: {ident}')
        text = path.read_text(encoding='utf-8')
        if not text.startswith('# Reviewed publication\n') or ident not in text:
            raise ValueError(f'reviewed publication rendering mismatch: {ident}')
        count += 1
    return count


def _record(root, value, existing=None):
    if not isinstance(value, dict) or set(value) - FIELDS or FIELDS - {'supersedes'} - set(value):
        raise ValueError('publication has missing or unknown fields')
    if type(value['schema_version']) is not int or value['schema_version'] != 1:
        raise ValueError('schema_version must be 1')
    for key in ('title', 'reviewer'):
        if not isinstance(value[key], str) or not value[key].strip():
            raise ValueError(f'{key} must be nonempty text')
    reviewed = datetime.fromisoformat(value['reviewed_at'].replace('Z', '+00:00'))
    if reviewed.tzinfo is None:
        raise ValueError('reviewed_at requires a timezone')
    if not isinstance(value['claims'], list) or not value['claims']:
        raise ValueError('publication requires at least one claim')
    record = {'schema_version': 1, 'title': value['title'].strip(),
              'reviewer': value['reviewer'].strip(), 'reviewed_at': value['reviewed_at'],
              'claims': [_claim(root, claim) for claim in value['claims']]}
    if 'supersedes' in value:
        parent = value['supersedes']
        if not isinstance(parent, str) or parent == existing:
            raise ValueError('supersedes must name an earlier publication')
        _chain(root, parent, set())
        record['supersedes'] = parent
    return record


def _claim(root, claim):
    if not isinstance(claim, dict) or set(claim) - CLAIM_FIELDS or {'statement', 'disposition'} - set(claim):
        raise ValueError('invalid publication claim')
    if not isinstance(claim['statement'], str) or not claim['statement'].strip():
        raise ValueError('claim statement must be nonempty text')
    if claim['disposition'] not in {'included', 'excluded'}:
        raise ValueError('claim disposition must be included or excluded')
    item = {'statement': claim['statement'].strip(), 'disposition': claim['disposition']}
    if 'capture_id' in claim:
        get(root, 'captures', claim['capture_id'])
        item['capture_id'] = claim['capture_id']
    if claim['disposition'] == 'included':
        if 'capture_id' not in item or 'exclusion_reason' in claim:
            raise ValueError('an included claim requires a capture and no exclusion reason')
    else:
        reason = claim.get('exclusion_reason')
        if not isinstance(reason, str) or not reason.strip():
            raise ValueError('an excluded claim requires an exclusion reason')
        item['exclusion_reason'] = reason.strip()
    return item


def _chain(root, ident, seen):
    if ident in seen:
        raise ValueError('publication correction cycle')
    seen.add(ident)
    try:
        record = get(root, 'publications', ident)
    except OSError as exc:
        raise ValueError('supersedes must name an earlier publication') from exc
    if 'supersedes' in record:
        _chain(root, record['supersedes'], seen)


def _render(root, ident, record):
    lines = ['# Reviewed publication', '',
             'This file is a reviewed publication. It is not a generated daily, weekly, or external draft.',
             '', f'- Revision: `{ident}`', f"- Title: {record['title']}",
             f"- Reviewer: {record['reviewer']}", f"- Reviewed: {record['reviewed_at']}"]
    if 'supersedes' in record:
        lines.append(f"- Supersedes: `{record['supersedes']}`")
    lines += ['', '## Claims', '']
    for claim in record['claims']:
        lines.append(f"- {claim['disposition']}: {claim['statement']}")
        if 'capture_id' in claim:
            lines.append(f"  - Capture: `{claim['capture_id']}`")
        if 'exclusion_reason' in claim:
            lines.append(f"  - Excluded because: {claim['exclusion_reason']}")
    path = Path(root) / 'digests' / 'reviewed' / f'{ident}.md'
    path.parent.mkdir(parents=True, exist_ok=True)
    path.write_text('\n'.join(lines) + '\n', encoding='utf-8')