#!/usr/bin/env python3
"""Check that all env vars used in the codebase are documented in .env.example."""

import os
import re
import sys

REPO_ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))

# Matches `const foo = "ENV_NAME"` (with optional explicit string type) on a
# single line, plus the same declarations inside a `const ( ... )` block.
CONST_SINGLE_RE = re.compile(r'const\s+(\w+)(?:\s+string)?\s*=\s*"([A-Z_][A-Z0-9_]*)"')
CONST_BLOCK_RE = re.compile(r'const\s*\(([^)]*)\)')
CONST_BLOCK_ITEM_RE = re.compile(r'(\w+)(?:\s+string)?\s*=\s*"([A-Z_][A-Z0-9_]*)"')

# Matches os.Getenv / os.LookupEnv with either a string literal
# (os.Getenv("VAR")) or an identifier (os.Getenv(varName)) that may be a
# const holding the env var name (const-indirect reads).
GETENV_RE = re.compile(
    r'os\.(?:Getenv|LookupEnv)\(\s*(?:"([A-Z_][A-Z0-9_]*)"|([A-Za-z_]\w*))\s*\)'
)


def go_const_map():
    """Return {package_name: {const_name: "ENV_NAME"}} from all backend Go files.

    Consts are package-scoped in Go: a const may be defined in one file and
    referenced from os.Getenv in another file of the same package (e.g.
    twoFAPepperEnv defined in twofa.go, read in twofa_prod.go), so collection
    must be per package rather than per file.
    """
    consts = {}  # package -> {name -> value}
    go_dir = os.path.join(REPO_ROOT, 'backend')
    for root, dirs, files in os.walk(go_dir):
        dirs[:] = [d for d in dirs if d not in ('vendor', '.git', 'node_modules')]
        for f in files:
            if not f.endswith('.go'):
                continue
            path = os.path.join(root, f)
            with open(path) as fh:
                content = fh.read()
            pkg_match = re.search(r'^package\s+(\w+)', content, re.MULTILINE)
            if not pkg_match:
                continue
            pkg = pkg_match.group(1)
            pkg_consts = consts.setdefault(pkg, {})
            for name, value in CONST_SINGLE_RE.findall(content):
                pkg_consts[name] = value
            for block in CONST_BLOCK_RE.findall(content):
                for name, value in CONST_BLOCK_ITEM_RE.findall(block):
                    pkg_consts[name] = value
    return consts


def find_env_vars_in_code():
    """Find all env vars read in the codebase (os.Getenv/os.LookupEnv in backend
    Go files, import.meta.env.VITE_* in frontend files)."""
    env_vars = set()
    consts = go_const_map()

    # Search backend Go files for os.Getenv / os.LookupEnv reads, including
    # const-indirect reads (os.Getenv(constName) resolved via the const map).
    go_dir = os.path.join(REPO_ROOT, 'backend')
    for root, dirs, files in os.walk(go_dir):
        dirs[:] = [d for d in dirs if d not in ('vendor', '.git', 'node_modules')]
        for f in files:
            if not f.endswith('.go'):
                continue
            path = os.path.join(root, f)
            with open(path) as fh:
                content = fh.read()
            pkg_match = re.search(r'^package\s+(\w+)', content, re.MULTILINE)
            pkg_consts = consts.get(pkg_match.group(1), {}) if pkg_match else {}
            for literal, identifier in GETENV_RE.findall(content):
                if literal:
                    env_vars.add(literal)
                elif identifier in pkg_consts:
                    env_vars.add(pkg_consts[identifier])
                # Non-const identifiers (e.g. function params like getEnv(key))
                # cannot be resolved to a specific env var — skip them.

    # Search frontend files for import.meta.env.VITE_* / import.meta.env.*
    frontend_dir = os.path.join(REPO_ROOT, 'frontend')
    for root, dirs, files in os.walk(frontend_dir):
        dirs[:] = [d for d in dirs if d not in ('.git', 'node_modules', 'build')]
        for f in files:
            if f.endswith(('.ts', '.svelte', '.js')):
                path = os.path.join(root, f)
                with open(path) as fh:
                    for line in fh:
                        m = re.findall(r'import\.meta\.env\.([A-Z_][A-Z0-9_]*)', line)
                        env_vars.update(m)

    # Vite built-ins (DEV, PROD, SSR, MODE, BASE_URL, BUILD) are provided by Vite
    # itself and cannot be defined in .env.example — never treat them as user env vars.
    env_vars -= {'DEV', 'PROD', 'SSR', 'MODE', 'BASE_URL', 'BUILD'}

    return sorted(env_vars)


def find_documented_vars():
    """Find all env vars documented in .env.example."""
    env_path = os.path.join(REPO_ROOT, '.env.example')
    documented = set()
    if os.path.exists(env_path):
        with open(env_path) as fh:
            for line in fh:
                line = line.strip()
                if line and not line.startswith('#') and '=' in line:
                    var_name = line.split('=')[0].strip()
                    if var_name:
                        documented.add(var_name)
    return documented


def main():
    code_vars = find_env_vars_in_code()
    documented = find_documented_vars()

    undocumented = [v for v in code_vars if v not in documented]

    if undocumented:
        print("ERROR: The following env vars are used in code but not documented in .env.example:\n")
        for v in undocumented:
            print(f"  {v}")
        print(f"\nTotal: {len(undocumented)} undocumented vars out of {len(code_vars)} total")
        sys.exit(1)
    else:
        print(f"OK: All {len(code_vars)} env vars used in code are documented in .env.example")
        sys.exit(0)


if __name__ == '__main__':
    main()