"""Plugin: hash strings and identify hash types."""

from __future__ import annotations

import hashlib
import re

from derp.plugin import command

_ALGOS = ("md5", "sha1", "sha256", "sha512")

# Patterns for hash identification (length -> possible types)
_HASH_PATTERNS: list[tuple[str, int, str]] = [
    (r"^[a-fA-F0-9]{32}$", 32, "MD5"),
    (r"^[a-fA-F0-9]{40}$", 40, "SHA-1"),
    (r"^[a-fA-F0-9]{56}$", 56, "SHA-224"),
    (r"^[a-fA-F0-9]{64}$", 64, "SHA-256 / SHA3-256"),
    (r"^[a-fA-F0-9]{96}$", 96, "SHA-384 / SHA3-384"),
    (r"^[a-fA-F0-9]{128}$", 128, "SHA-512 / SHA3-512"),
    (r"^\$2[aby]\$\d{2}\$.{53}$", 0, "bcrypt"),
    (r"^\$6\$", 0, "sha512crypt"),
    (r"^\$5\$", 0, "sha256crypt"),
    (r"^\$1\$", 0, "md5crypt"),
    (r"^[a-fA-F0-9]{16}$", 16, "MySQL 3.x / Half MD5"),
    (r"^\*[a-fA-F0-9]{40}$", 0, "MySQL 4.1+"),
]


@command("hash", help="Hash text: !hash [algo] <text>")
async def cmd_hash(bot, message):
    """Generate hash digests.

    !hash hello          -> MD5, SHA1, SHA256
    !hash sha512 hello   -> specific algorithm
    """
    parts = message.text.split(None, 2)
    if len(parts) < 2:
        await bot.reply(message, f"Usage: !hash [{'|'.join(_ALGOS)}] <text>")
        return

    # Check if first arg is an algorithm name
    if len(parts) >= 3 and parts[1].lower() in _ALGOS:
        algo = parts[1].lower()
        text = parts[2]
        digest = hashlib.new(algo, text.encode()).hexdigest()
        await bot.reply(message, f"{algo}: {digest}")
        return

    # No algorithm specified -- show all common hashes
    text = message.text.split(None, 1)[1]
    results = []
    for algo in ("md5", "sha1", "sha256"):
        digest = hashlib.new(algo, text.encode()).hexdigest()
        results.append(f"{algo}:{digest}")
    await bot.reply(message, " ".join(results))


@command("hashid", help="Identify hash type: !hashid <hash>")
async def cmd_hashid(bot, message):
    """Identify a hash type by its format and length."""
    parts = message.text.split(None, 1)
    if len(parts) < 2:
        await bot.reply(message, "Usage: !hashid <hash>")
        return

    value = parts[1].strip()
    matches = []
    for pattern, _, name in _HASH_PATTERNS:
        if re.match(pattern, value):
            matches.append(name)

    if matches:
        await bot.reply(message, f"Possible: {', '.join(matches)}")
    else:
        await bot.reply(message, f"Unknown hash format (length: {len(value)})")