from __future__ import annotations

import hashlib
import re
from pathlib import Path


class MemoryStore:
    def __init__(self, cwd: Path) -> None:
        self.cwd = cwd.resolve()
        self.root = Path.home() / ".config" / "cc-slim" / "memory" / self._sanitize_cwd(self.cwd)
        self.root.mkdir(parents=True, exist_ok=True)
        self.ensure_structure()

    def ensure_structure(self) -> None:
        path = self.path()
        if not path.exists():
            path.write_text(self._default_template(), encoding="utf-8")
            return

        existing = path.read_text(encoding="utf-8").strip()
        if self._is_structured(existing):
            return

        migrated = self._default_template(existing)
        path.write_text(migrated, encoding="utf-8")

    def append(self, text: str) -> str:
        content = self.read().rstrip()
        entry = self._format_scratch_entry(text)
        updated = f"{content}\n\n{entry}\n"
        self.path().write_text(updated, encoding="utf-8")
        return "Scratch Notes"

    def read(self) -> str:
        self.ensure_structure()
        return self.path().read_text(encoding="utf-8").strip()

    def path(self) -> Path:
        return self.root / "MEMORY.md"

    def _default_template(self, scratch_notes: str = "") -> str:
        scratch = self._format_scratch_entry(scratch_notes) if scratch_notes.strip() else ""
        template = (
            "# Memory\n\n"
            "## User Memory\n\n"
            "## Project Memory\n\n"
            "## Constraints\n\n"
            "## Consolidated Facts\n\n"
            "## Scratch Notes\n"
        )
        return f"{template}\n{scratch}\n" if scratch else f"{template}\n"

    def _format_scratch_entry(self, text: str) -> str:
        lines = [line.rstrip() for line in text.strip().splitlines() if line.strip()]
        if not lines:
            return ""
        if len(lines) == 1:
            return f"- {lines[0]}"
        tail = "\n".join(f"  {line}" for line in lines[1:])
        return f"- {lines[0]}\n{tail}"

    def _is_structured(self, text: str) -> bool:
        required_sections = [
            "# Memory",
            "## User Memory",
            "## Project Memory",
            "## Constraints",
            "## Consolidated Facts",
            "## Scratch Notes",
        ]
        return all(section in text for section in required_sections)

    def _sanitize_cwd(self, cwd: Path) -> str:
        text = re.sub(r"[^A-Za-z0-9._-]+", "_", str(cwd))
        digest = hashlib.sha1(str(cwd).encode("utf-8")).hexdigest()[:8]
        return f"{text[:48]}-{digest}"