#!/usr/bin/env python3
"""
Automated cache-busting version bump utility for TreeTrack.

Updates:
- static/sw.js: const VERSION = <timestamp>
- static/index.html and static/map.html:
  * inline currentVersion = '<version>'
  * inline timestamp = '<timestamp>'
  * script tag query params (?v=<version>&t=<timestamp>) for tree-track-app.js and map.js

Usage examples:
  python scripts/bump_cache.py --now                # bump timestamp only
  python scripts/bump_cache.py --bump patch         # bump version 1.2.3 -> 1.2.4 and timestamp
  python scripts/bump_cache.py --set-version 5.1.2  # set specific version and bump timestamp

This script maintains state in version.json at repository root.
"""

import argparse
import json
import os
import re
import sys
import time
from pathlib import Path

ROOT = Path(__file__).resolve().parents[1]
VERSION_FILE = ROOT / 'version.json'
FILES = {
    'sw': ROOT / 'static' / 'sw.js',
    'index': ROOT / 'static' / 'index.html',
    'map': ROOT / 'static' / 'map.html',
}

SEMVER_RE = re.compile(r"^(\d+)\.(\d+)\.(\d+)$")


def read_text(p: Path) -> str:
    try:
        return p.read_text(encoding='utf-8')
    except FileNotFoundError:
        print(f"Error: file not found: {p}", file=sys.stderr)
        sys.exit(1)


def write_text(p: Path, content: str) -> None:
    p.write_text(content, encoding='utf-8', newline='\n')


def bump_semver(version: str, which: str) -> str:
    m = SEMVER_RE.match(version)
    if not m:
        raise ValueError(f"Invalid semver: {version}")
    major, minor, patch = map(int, m.groups())
    if which == 'major':
        major += 1
        minor = 0
        patch = 0
    elif which == 'minor':
        minor += 1
        patch = 0
    elif which == 'patch':
        patch += 1
    else:
        raise ValueError(f"Unknown bump type: {which}")
    return f"{major}.{minor}.{patch}"


def load_version() -> dict:
    if VERSION_FILE.exists():
        with VERSION_FILE.open('r', encoding='utf-8') as f:
            data = json.load(f)
            # minimal validation
            if 'version' not in data or 'timestamp' not in data:
                raise ValueError('version.json missing required fields')
            return data
    # default if not present
    return {
        'version': '0.1.0',
        'timestamp': int(time.time()),
    }


def save_version(version: str, timestamp: int) -> None:
    with VERSION_FILE.open('w', encoding='utf-8') as f:
        json.dump({'version': version, 'timestamp': timestamp}, f, indent=2)
        f.write('\n')


def update_sw_js(content: str, timestamp: int) -> str:
    # Replace: const VERSION = 1234567890;
    new_content, n = re.subn(r"(const\s+VERSION\s*=\s*)(\d+)(\s*;)",
                             rf"\g<1>{timestamp}\g<3>", content)
    if n == 0:
        print('Warning: VERSION not updated in sw.js (pattern not found)')
    return new_content


def update_html(content: str, version: str, timestamp: int, is_index: bool) -> str:
    updated = content

    # Update inline currentVersion = '<version>'
    updated, n_ver = re.subn(r"(currentVersion\s*=\s*')[^']*(')", rf"\g<1>{version}\g<2>", updated)
    if n_ver == 0:
        print('Warning: currentVersion not updated (pattern not found)')

    # Update inline timestamp = '<timestamp>'
    updated, n_ts = re.subn(r"(timestamp\s*=\s*')[^']*(')", rf"\g<1>{timestamp}\g<2>", updated)
    if n_ts == 0:
        print('Warning: timestamp not updated (pattern not found)')

    # Update script tag query params
    # For index.html: tree-track-app.js?v=X&t=Y
    # For map.html:   /static/map.js?v=X&t=Y (we use same version for simplicity)
    if is_index:
        updated, n_tag = re.subn(r"(tree-track-app\.js\?v=)[^&']+(\&t=)[^'\"]+",
                                 rf"\g<1>{version}\g<2>{timestamp}", updated)
        if n_tag == 0:
            print('Warning: tree-track-app.js cache params not updated (pattern not found)')
    else:
        updated, n_tag = re.subn(r"(/static/map\.js\?v=)[^&']+(\&t=)[^'\"]+",
                                 rf"\g<1>{version}\g<2>{timestamp}", updated)
        if n_tag == 0:
            print('Warning: map.js cache params not updated (pattern not found)')

    return updated


def main():
    parser = argparse.ArgumentParser(description='Bump cache-busting version/timestamp across files')
    group = parser.add_mutually_exclusive_group()
    group.add_argument('--bump', choices=['major', 'minor', 'patch'], help='Semver bump type')
    group.add_argument('--set-version', help='Set explicit version (x.y.z)')
    parser.add_argument('--timestamp', type=int, help='Set explicit timestamp (epoch seconds)')
    parser.add_argument('--now', action='store_true', help='Use current time as timestamp')
    args = parser.parse_args()

    state = load_version()
    version = state['version']
    timestamp = state['timestamp']

    # Determine new version
    if args.set_version:
        if not SEMVER_RE.match(args.set_version):
            print('Error: --set-version must be in x.y.z format', file=sys.stderr)
            sys.exit(2)
        version = args.set_version
    elif args.bump:
        version = bump_semver(version, args.bump)

    # Determine new timestamp
    if args.timestamp is not None:
        timestamp = int(args.timestamp)
    elif args.now or args.set_version or args.bump:
        timestamp = int(time.time())

    # Save version state
    save_version(version, timestamp)

    # Update files
    sw_path = FILES['sw']
    index_path = FILES['index']
    map_path = FILES['map']

    sw_content = read_text(sw_path)
    index_content = read_text(index_path)
    map_content = read_text(map_path)

    sw_new = update_sw_js(sw_content, timestamp)
    index_new = update_html(index_content, version, timestamp, is_index=True)
    map_new = update_html(map_content, version, timestamp, is_index=False)

    if sw_new != sw_content:
        write_text(sw_path, sw_new)
        print(f"Updated {sw_path}")
    if index_new != index_content:
        write_text(index_path, index_new)
        print(f"Updated {index_path}")
    if map_new != map_content:
        write_text(map_path, map_new)
        print(f"Updated {map_path}")

    print(f"Done. version={version} timestamp={timestamp}")


if __name__ == '__main__':
    main()