"""FlowDeck — Sharing, Publishing & Recents API (v4.0)."""
from __future__ import annotations

import logging
import re
import unicodedata
from datetime import datetime

from fastapi import APIRouter, HTTPException, Request

from app.auth.session import SessionManager
from app.db import get_conn

logger = logging.getLogger(__name__)
router = APIRouter(tags=["sharing"], prefix="/api")


def _require_auth(request: Request) -> dict:
    """Require an authenticated session. Returns user dict or raises 401."""
    user = SessionManager.decode_session(request.cookies.get("flowdeck_session", ""))
    if not user:
        raise HTTPException(status_code=401, detail="Authentication required")
    return user


def _slugify(title: str) -> str:
    """Generate a URL-safe slug from a page title."""
    slug = unicodedata.normalize("NFKD", title).encode("ascii", "ignore").decode("ascii")
    slug = re.sub(r"[^\w\s-]", "", slug.lower())
    slug = re.sub(r"[-\s]+", "-", slug).strip("-")
    return slug or "untitled"


# ── Page Sharing ──


@router.post("/pages/{page_id}/share")
async def share_page(page_id: int, request: Request):
    """Invite a user, an email, or a group to a page."""
    user = _require_auth(request)
    body = await request.json() if request.headers.get("content-type") else {}
    target_user_id = body.get("user_id")
    target_group_id = body.get("group_id")
    email = body.get("email", "")
    permission = body.get("permission", "view")

    if permission not in ("view", "comment", "edit"):
        raise HTTPException(400, "Invalid permission. Use view, comment, or edit.")

    if not target_user_id and not target_group_id and not email:
        raise HTTPException(400, "Provide user_id, group_id or email to share with.")

    # Bridge share permission (view/comment/edit) → granular role
    # (viewer/commenter/editor) so page_permissions grants stay in sync.
    _SHARE_TO_ROLE = {"view": "viewer", "comment": "commenter", "edit": "editor"}

    with get_conn() as conn:
        # Verify page exists
        page = conn.execute("SELECT id, title FROM pages WHERE id=?", (page_id,)).fetchone()
        if not page:
            raise HTTPException(404, "Page not found")

        # Verify target user exists if user_id given
        if target_user_id:
            target = conn.execute("SELECT id FROM users WHERE id=?", (target_user_id,)).fetchone()
            if not target:
                raise HTTPException(404, "Target user not found")

        # Verify target group exists if group_id given
        if target_group_id:
            gtarget = conn.execute("SELECT id FROM user_groups WHERE id=?", (target_group_id,)).fetchone()
            if not gtarget:
                raise HTTPException(404, "Target group not found")

        # Upsert to avoid duplicates: update the existing permission if the same
        # target (user, group or email) is already shared on this page.
        target_row = None
        if target_user_id:
            target_row = conn.execute(
                "SELECT id FROM page_shares WHERE page_id=? AND shared_with_user_id=?",
                (page_id, target_user_id),
            ).fetchone()
        elif target_group_id:
            target_row = conn.execute(
                "SELECT id FROM page_shares WHERE page_id=? AND shared_with_group_id=?",
                (page_id, target_group_id),
            ).fetchone()
        elif email:
            target_row = conn.execute(
                """SELECT id FROM page_shares
                   WHERE page_id=? AND shared_with_email=? AND shared_with_user_id IS NULL AND shared_with_group_id IS NULL""",
                (page_id, email.strip()),
            ).fetchone()

        if target_row:
            conn.execute(
                "UPDATE page_shares SET permission=?, created_by=? WHERE id=?",
                (permission, user["id"], target_row["id"]),
            )
            share_id = target_row["id"]
        else:
            if not email:
                email = ""
            try:
                cur = conn.execute(
                    """INSERT INTO page_shares (page_id, shared_with_user_id, shared_with_group_id, shared_with_email, permission, created_by)
                       VALUES (?, ?, ?, ?, ?, ?)""",
                    (page_id, target_user_id, target_group_id, email.strip(), permission, user["id"]),
                )
            except Exception:
                # Fallback for DBs where the migration has not run yet
                cur = conn.execute(
                    """INSERT INTO page_shares (page_id, shared_with_user_id, shared_with_email, permission, created_by)
                       VALUES (?, ?, ?, ?, ?)""",
                    (page_id, target_user_id, email.strip(), permission, user["id"]),
                )
            share_id = cur.lastrowid
        conn.execute("UPDATE pages SET is_shared=1 WHERE id=?", (page_id,))
        # ── Mirror group shares into page_permissions so the ACL used by
        # PermissionManager (can_view/edit/comment) grants real access to
        # every group member. Best-effort: never break legacy page_shares.
        if target_group_id:
            try:
                _mirror_share_grant(conn, page_id, target_group_id, _SHARE_TO_ROLE[permission], user["id"])
            except Exception:
                logger.warning("share→page_permissions mirror failed (page=%s group=%s)", page_id, target_group_id)
        conn.commit()

    return {
        "id": share_id,
        "page_id": page_id,
        "shared_with_user_id": target_user_id,
        "shared_with_group_id": target_group_id,
        "shared_with_email": email,
        "permission": permission,
        "status": "shared",
    }


def _mirror_share_grant(conn, page_id: int, group_id: int, role: str, granted_by: int) -> None:
    """Upsert a ``page_permissions`` grant mirroring a group ``page_shares`` row.

    Keeps the granular ACL (used by ``PermissionManager``) in sync with what
    the share dialog shows, so invited groups get effective view/edit rights.
    """
    existing = conn.execute(
        "SELECT id FROM page_permissions WHERE page_id=? AND user_id IS NULL AND group_id=?",
        (page_id, group_id),
    ).fetchone()
    if existing:
        conn.execute("UPDATE page_permissions SET role=?, granted_by=? WHERE id=?",
                     (role, granted_by, existing["id"]))
    else:
        conn.execute(
            "INSERT INTO page_permissions (page_id, user_id, group_id, role, granted_by) "
            "VALUES (?, NULL, ?, ?, ?)",
            (page_id, group_id, role, granted_by),
        )


def _mirror_share_revoke(conn, page_id: int, group_id: int) -> None:
    """Remove the mirrored grant when a group share is updated away or deleted."""
    conn.execute(
        "DELETE FROM page_permissions WHERE page_id=? AND user_id IS NULL AND group_id=?",
        (page_id, group_id),
    )


@router.put("/pages/{page_id}/share/{share_id}", description="Update a share's permission.")
async def update_share_permission(page_id: int, share_id: int, request: Request):
    """Change the permission level of an existing share entry."""
    user = _require_auth(request)

    body = await request.json() if request.headers.get("content-type") else {}
    permission = body.get("permission", "")

    if permission not in ("view", "comment", "edit"):
        raise HTTPException(400, "Invalid permission. Use view, comment, or edit.")

    with get_conn() as conn:
        row = conn.execute(
            "SELECT id, shared_with_group_id FROM page_shares WHERE id=? AND page_id=?",
            (share_id, page_id),
        ).fetchone()
        if not row:
            raise HTTPException(404, "Share entry not found")

        conn.execute(
            "UPDATE page_shares SET permission=? WHERE id=?",
            (permission, share_id),
        )
        # Keep the mirrored ACL grant in sync for group shares.
        try:
            gid = row["shared_with_group_id"] if "shared_with_group_id" in row.keys() else None
        except Exception:
            gid = None
        if gid:
            try:
                _mirror_share_grant(conn, page_id, gid,
                                    {"view": "viewer", "comment": "commenter", "edit": "editor"}[permission],
                                    user["id"])
            except Exception:
                logger.warning("share→page_permissions mirror failed (share=%s)", share_id)
        conn.commit()

    return {"status": "updated", "share_id": share_id, "permission": permission}


@router.delete("/pages/{page_id}/share/{share_id}")
async def remove_share(page_id: int, share_id: int, request: Request):
    """Remove a share invitation."""
    _require_auth(request)

    with get_conn() as conn:
        row = conn.execute(
            "SELECT id, shared_with_group_id FROM page_shares WHERE id=? AND page_id=?",
            (share_id, page_id),
        ).fetchone()
        if not row:
            raise HTTPException(404, "Share entry not found")

        conn.execute("DELETE FROM page_shares WHERE id=?", (share_id,))
        try:
            gid = row["shared_with_group_id"] if "shared_with_group_id" in row.keys() else None
        except Exception:
            gid = None
        if gid:
            try:
                _mirror_share_revoke(conn, page_id, gid)
            except Exception:
                logger.warning("share→page_permissions revoke failed (share=%s)", share_id)
        # If no more shares, unset is_shared
        remaining = conn.execute(
            "SELECT COUNT(*) AS c FROM page_shares WHERE page_id=?", (page_id,)
        ).fetchone()["c"]
        if remaining == 0:
            conn.execute("UPDATE pages SET is_shared=0 WHERE id=?", (page_id,))
        conn.commit()

    return {"status": "removed", "share_id": share_id}


@router.get("/pages/{page_id}/shares")
async def list_shares(page_id: int, request: Request):
    """Get all shares for a page."""
    _require_auth(request)

    with get_conn() as conn:
        page = conn.execute("SELECT id FROM pages WHERE id=?", (page_id,)).fetchone()
        if not page:
            raise HTTPException(404, "Page not found")

        try:
            rows = conn.execute(
                """SELECT s.*, u.login, u.full_name, u.avatar_url, g.name AS group_name
                   FROM page_shares s
                   LEFT JOIN users u ON s.shared_with_user_id = u.id
                   LEFT JOIN user_groups g ON s.shared_with_group_id = g.id
                   WHERE s.page_id=?
                   ORDER BY s.created_at DESC""",
                (page_id,),
            ).fetchall()
        except Exception:
            rows = conn.execute(
                """SELECT s.*, u.login, u.full_name, u.avatar_url
                   FROM page_shares s
                   LEFT JOIN users u ON s.shared_with_user_id = u.id
                   WHERE s.page_id=?
                   ORDER BY s.created_at DESC""",
                (page_id,),
            ).fetchall()

    return {
        "page_id": page_id,
        "shares": [
            {
                "id": r["id"],
                "shared_with_user_id": r["shared_with_user_id"],
                "shared_with_group_id": r["shared_with_group_id"] if "shared_with_group_id" in r.keys() else None,
                "shared_with_email": r["shared_with_email"],
                "permission": r["permission"],
                "created_at": r["created_at"],
                "created_by": r["created_by"],
                "user_login": r["login"],
                "user_full_name": r["full_name"],
                "user_avatar_url": r["avatar_url"],
                "group_name": r["group_name"] if "group_name" in r.keys() else None,
                "kind": "group" if (("shared_with_group_id" in r.keys() and r["shared_with_group_id"]) or ("group_name" in r.keys() and r["group_name"])) else "user",
            }
            for r in rows
        ],
    }


# ── Page Publishing ──


@router.post("/pages/{page_id}/publish")
async def publish_page(page_id: int, request: Request):
    """Publish a page (is_published=1) with a URL slug."""
    _require_auth(request)

    with get_conn() as conn:
        page = conn.execute(
            "SELECT id, title, is_published FROM pages WHERE id=?", (page_id,)
        ).fetchone()
        if not page:
            raise HTTPException(404, "Page not found")

        slug = _slugify(page["title"])
        # Ensure uniqueness by appending suffix if needed
        base_slug = slug
        counter = 1
        while conn.execute(
            "SELECT id FROM pages WHERE publish_slug=? AND id!=?", (slug, page_id)
        ).fetchone():
            slug = f"{base_slug}-{counter}"
            counter += 1

        conn.execute(
            "UPDATE pages SET is_published=1, publish_slug=? WHERE id=?",
            (slug, page_id),
        )
        conn.commit()

    return {
        "page_id": page_id,
        "is_published": True,
        "publish_slug": slug,
        "status": "published",
    }


@router.delete("/pages/{page_id}/publish")
async def unpublish_page(page_id: int, request: Request):
    """Unpublish a page."""
    _require_auth(request)

    with get_conn() as conn:
        page = conn.execute(
            "SELECT id, is_published FROM pages WHERE id=?", (page_id,)
        ).fetchone()
        if not page:
            raise HTTPException(404, "Page not found")

        conn.execute(
            "UPDATE pages SET is_published=0, publish_slug='' WHERE id=?",
            (page_id,),
        )
        conn.commit()

    return {
        "page_id": page_id,
        "is_published": False,
        "status": "unpublished",
    }


# ── Recents ──


@router.post("/recents/track")
async def track_recent(request: Request):
    """Record a page access in recents."""
    user = _require_auth(request)
    body = await request.json() if request.headers.get("content-type") else {}
    page_id = body.get("page_id")
    workspace = body.get("workspace", "")
    source_type = body.get("source_type", "local")

    if not page_id:
        raise HTTPException(400, "page_id is required")

    with get_conn() as conn:
        page = conn.execute("SELECT id FROM pages WHERE id=?", (page_id,)).fetchone()
        if not page:
            raise HTTPException(404, "Page not found")

        conn.execute(
            """INSERT INTO recents (user_id, page_id, workspace, source_type, accessed_at)
               VALUES (?, ?, ?, ?, ?)
               ON CONFLICT(user_id, page_id)
               DO UPDATE SET workspace=excluded.workspace,
                             source_type=excluded.source_type,
                             accessed_at=excluded.accessed_at""",
            (user["id"], page_id, workspace, source_type, datetime.utcnow().isoformat()),
        )
        conn.commit()

    return {
        "status": "tracked",
        "user_id": user["id"],
        "page_id": page_id,
        "accessed_at": datetime.utcnow().isoformat(),
    }