"""Reading a challenge's README header.

Only the template's header block is parsed:

    ### Challenge Name
    - Category: crypto
    - Difficulty: medium
    - Status: Testing Ready
    ...

People fill it in loosely, so the values are normalised here. Whether they are
good enough is decided in checks.py.
"""
from __future__ import annotations

import re
from dataclasses import dataclass, field

from .gitlab import Repo

FIELDS = ("Category", "Difficulty", "Event", "Author", "Tester", "Status")
HEADING_RE = re.compile(r"^\s{0,3}#{1,4}\s+(.+?)\s*$", re.M)
FIELD_RE = re.compile(r"^\s*[-*]\s*\**(?P<key>[A-Za-z ]+?)\**\s*:\s*(?P<val>.*?)\s*$", re.M)
# a value the author never touched: "[crypto, pwn, ...]" or "[Author Name]"
PLACEHOLDER_RE = re.compile(r"^\[.*\]$")
NO_TESTER_RE = re.compile(r"^(\?+|none|tester name|not found\b.*|tbd)(\s.*)?$", re.I)

STATUS_ORDER = ["Planning", "PoC Draft", "Testing Ready", "Tested", "Ready"]
STATUS_RE = re.compile(r"testing\s*ready|tested|ready|poc(?:\s*draft)?|planning", re.I)
STATUS_ICON = {"Planning": "⚪", "PoC Draft": "🟠", "Testing Ready": "🟡",
               "Tested": "🔵", "Ready": "🟢", None: "❔"}
BLOCKED_ICON = "⛔"
# what challenges.yml can say about a repo, and how the reports call it
SELECTIONS = {"included": "included", "abandoned": "abandoned", "postponed": "left for another CTF"}
CATEGORIES = ["crypto", "pwn", "web", "rev", "misc", "osint", "forensic", "hardware"]
DIFFICULTIES = ["intro", "easy", "medium", "hard"]
DIFF_RE = re.compile(r"intro|easy|medium|hard", re.I)
DIFF_RANGE_RE = re.compile(r"(intro|easy|medium|hard)\s*(?:-|–|/|\bto\b)\s*(intro|easy|medium|hard)", re.I)
CATEGORY_SPLIT_RE = re.compile(r"[,/&+]| and ")


def clean(v: str) -> str:
    v = re.sub(r"\\+([\[\]_*])", r"\1", v)  # markdown escapes, sometimes doubled
    return v.replace("**", "").strip()


def is_placeholder(v: str) -> bool:
    v = clean(v)
    return not v or bool(PLACEHOLDER_RE.match(v))


def stage_of(raw: str) -> tuple[str | None, bool]:
    """Map a free-text status onto STATUS_ORDER -> (stage, clear).

    "Tested with h4tum-chall-format" is clearly Tested. "Planning to PoC Draft"
    or a half-deleted option list is not; we take the least advanced stage it
    names, so nothing looks further along than it is, and call it unclear."""
    if is_placeholder(raw):
        return None, False
    found = set()
    for m in STATUS_RE.finditer(raw):
        w = m.group(0).lower()
        found.add("Testing Ready" if w.startswith("testing") else
                  "PoC Draft" if w.startswith("poc") else w.title())
    if not found:
        return None, False
    return min(found, key=STATUS_ORDER.index), len(found) == 1


def difficulty_of(raw: str) -> str | None:
    """"medium/hard", "medium-hard", "easy to medium" -> a range "medium-hard"."""
    if is_placeholder(raw):
        return None
    m = DIFF_RANGE_RE.search(raw)
    if m:
        ends = sorted({m.group(1).lower(), m.group(2).lower()}, key=DIFFICULTIES.index)
        return "-".join(ends) if len(ends) > 1 else ends[0]
    # prose like "currently medium, maybe also an easy and a hard version": the first one
    m = DIFF_RE.search(raw)
    return m.group(0).lower() if m else None


def difficulty_rank(d: str | None) -> float:
    if not d:
        return 99
    ends = d.split("-")
    return sum(DIFFICULTIES.index(e) for e in ends) / len(ends)


@dataclass
class Challenge:
    repo: Repo
    name: str = ""
    fields: dict = field(default_factory=dict)
    # filled in by overview.collect(), see selection.py and checks.py
    selection: str | None = None                      # None: not in challenges.yml
    skip_checks: list = field(default_factory=list)
    problems: list = field(default_factory=list)  # readme_problems()
    blockers: list = field(default_factory=list)  # repo_blockers()

    def get(self, key: str, dash: str = "—") -> str:
        v = clean(self.fields.get(key, ""))
        return dash if is_placeholder(v) else v

    # -- derived -----------------------------------------------------------
    @property
    def named(self) -> bool:
        return bool(self.name) and not is_placeholder(self.name)

    @property
    def title(self) -> str:
        return self.name if self.named else self.repo.path

    @property
    def touched(self) -> bool:
        """Did anyone put *any* real content in the README template?"""
        return self.named or any(not is_placeholder(self.fields.get(f, "")) for f in FIELDS)

    @property
    def status_raw(self) -> str:
        return self.get("Status")

    @property
    def stage(self) -> str | None:
        return stage_of(self.fields.get("Status", ""))[0]

    @property
    def difficulty(self) -> str | None:
        return difficulty_of(self.fields.get("Difficulty", ""))

    @property
    def category(self) -> str | None:
        """The first category named; "rev, misc" counts as rev."""
        raw = self.get("Category", "")
        first = CATEGORY_SPLIT_RE.split(raw)[0].strip().lower()
        return first or None

    @property
    def included(self) -> bool:
        return self.selection == "included"

    @property
    def claims_testable(self) -> bool:
        """The README says Testing Ready or beyond; checks.is_testable() also asks the repo."""
        return bool(self.stage) and STATUS_ORDER.index(self.stage) >= STATUS_ORDER.index("Testing Ready")

    @property
    def icon(self) -> str:
        return BLOCKED_ICON if self.blockers else STATUS_ICON[self.stage]

    @property
    def has_tester(self) -> bool:
        t = self.get("Tester", "")
        return bool(t) and not NO_TESTER_RE.match(t)


def parse_challenge(repo: Repo) -> Challenge:
    c = Challenge(repo=repo)
    text = repo.readme or ""
    m = HEADING_RE.search(text)
    if m:
        c.name = clean(m.group(1))
    for fm in FIELD_RE.finditer(text):
        key = fm.group("key").strip().title()
        if key in FIELDS and key not in c.fields:
            c.fields[key] = fm.group("val")
    return c