"""MCP tools for SYNO.Docker.Image: list, check updates, delete."""

from __future__ import annotations

import logging
from datetime import UTC, datetime
from typing import TYPE_CHECKING, Any

if TYPE_CHECKING:
    from mcp.server.fastmcp import FastMCP

    from mcp_synology_container.config import AppConfig
    from mcp_synology_container.dsm_client import DsmClient

logger = logging.getLogger(__name__)


def _human_size(size_bytes: int) -> str:
    """Convert byte count to human-readable string (GiB / MiB / KiB)."""
    if size_bytes >= 1024**3:
        return f"{size_bytes / 1024**3:.1f} GiB"
    if size_bytes >= 1024**2:
        return f"{size_bytes / 1024**2:.0f} MiB"
    if size_bytes >= 1024:
        return f"{size_bytes / 1024:.0f} KiB"
    return f"{size_bytes} B"


def _format_created(ts: int) -> str:
    """Format a Unix timestamp as a UTC date string."""
    if not ts:
        return "unknown"
    try:
        return datetime.fromtimestamp(ts, tz=UTC).strftime("%Y-%m-%d")
    except (OSError, OverflowError, ValueError):
        return "unknown"


async def _filter_images_for_project(
    client: DsmClient,
    project_name: str,
    all_images: list[dict[str, Any]],
) -> list[dict[str, Any]]:
    """Filter images to those used by a specific project.

    Fetches project details and cross-references container image IDs.
    Falls back to returning all images if project details are unavailable.

    Args:
        client: DsmClient instance.
        project_name: Project name to filter for.
        all_images: Full list of images from SYNO.Docker.Image.

    Returns:
        Subset of images used by the project.
    """
    try:
        list_data = await client.request("SYNO.Docker.Project", "list")
        projects: dict[str, Any] = list_data if isinstance(list_data, dict) else {}
        project_entry = next((p for p in projects.values() if p.get("name") == project_name), None)

        if not project_entry:
            return []

        project_id = project_entry.get("id", "")
        detail_data = await client.request(
            "SYNO.Docker.Project",
            "get",
            params={"id": project_id},
        )

        containers = detail_data.get("containers", []) or []
        image_ids: set[str] = set()
        image_names: set[str] = set()

        for container in containers:
            img_id = container.get("Image", "")
            if img_id:
                image_ids.add(img_id)
            cfg_image = container.get("Config", {}).get("Image", "")
            if cfg_image:
                name = cfg_image.split(":")[0] if ":" in cfg_image else cfg_image
                image_names.add(name)

        result = []
        for img in all_images:
            img_id = img.get("id", "")
            repo = img.get("repository", "")
            if img_id in image_ids or repo in image_names:
                result.append(img)

        return result

    except Exception as e:
        logger.debug("Could not filter images for project '%s': %s", project_name, e)
        return all_images


def register_images(mcp: FastMCP, config: AppConfig, client: DsmClient) -> None:
    """Register all image management tools with the MCP server."""

    @mcp.tool()
    async def list_images() -> str:
        """List all local Docker images sorted by size (largest first).

        Shows name:tag, size, creation date, and whether the image is
        currently used by at least one container.
        """
        try:
            img_data = await client.request(
                "SYNO.Docker.Image",
                "list",
                params={"limit": "-1", "offset": "0", "show_dsm": "false"},
            )
        except Exception as e:
            return f"Error listing images: {e}"

        images: list[dict[str, Any]] = img_data.get("images", [])
        if not images:
            return "No local images found."

        # Collect image IDs in use by containers
        in_use_ids: set[str] = set()
        try:
            ctr_data = await client.request(
                "SYNO.Docker.Container",
                "list",
                params={"limit": "-1", "offset": "0", "type": "all"},
            )
            for ctr in ctr_data.get("containers", []):
                img_id = ctr.get("image_id") or ctr.get("ImageID") or ctr.get("Image", "")
                if img_id:
                    in_use_ids.add(img_id)
        except Exception as e:
            logger.debug("Could not fetch containers for in-use check: %s", e)

        # Sort by size descending
        images_sorted = sorted(images, key=lambda x: x.get("size", 0), reverse=True)

        total_size = sum(img.get("size", 0) for img in images)
        lines = [f"Local images ({len(images)} total, {_human_size(total_size)}):", ""]

        for img in images_sorted:
            repo = img.get("repository", "<none>")
            tags = img.get("tags") or ["<none>"]
            tag_str = ", ".join(tags)
            size = _human_size(img.get("size", 0))
            created = _format_created(img.get("created", 0))
            img_id = img.get("id", "")
            used_marker = "  [in use]" if img_id in in_use_ids else ""
            upgradable = "  [update available]" if img.get("upgradable") else ""
            lines.append(f"  {repo}:{tag_str}  {size}  {created}{used_marker}{upgradable}")

        return "\n".join(lines)

    @mcp.tool()
    async def delete_image(image_id: str, confirmed: bool = False) -> str:
        """Delete a local Docker image by name:tag or image ID hash.

        Without confirmed=True, returns a preview of what would be deleted.
        Refuses deletion if the image is used by any container.

        Args:
            image_id: Image reference as "name:tag" (e.g. "nginx:1.24")
                      or a full/short image hash (e.g. "sha256:14300de7…").
            confirmed: Must be True to actually delete. Default False shows
                       a preview only.
        """
        # Parse name:tag
        name, _, tag = image_id.partition(":")
        if not tag:
            tag = "latest"

        # Fetch the local image list for size reporting and in-use detection
        try:
            img_data = await client.request(
                "SYNO.Docker.Image",
                "list",
                params={"limit": "-1", "offset": "0", "show_dsm": "false"},
            )
        except Exception as e:
            return f"Error fetching image list: {e}"

        images: list[dict[str, Any]] = img_data.get("images", [])

        # Locate the target image by name+tag or hash prefix
        is_hash = image_id.startswith("sha256:") or (len(image_id) >= 12 and ":" not in image_id)
        target: dict[str, Any] | None = None

        for img in images:
            if is_hash:
                img_hash = img.get("id", "")
                if img_hash == image_id or img_hash.startswith(image_id):
                    target = img
                    break
            else:
                repo = img.get("repository", "")
                img_tags = img.get("tags") or []
                if repo == name and tag in img_tags:
                    target = img
                    break

        if target is None:
            return f"Image '{image_id}' not found locally."

        # Resolve display info from the found image
        repo = target.get("repository", name)
        img_tags = target.get("tags") or [tag]
        display_name = f"{repo}:{img_tags[0]}"
        size_str = _human_size(target.get("size", 0))
        img_hash = target.get("id", "")

        # Check if image is in use by any container
        in_use_by: list[str] = []
        try:
            ctr_data = await client.request(
                "SYNO.Docker.Container",
                "list",
                params={"limit": "-1", "offset": "0", "type": "all"},
            )
            for ctr in ctr_data.get("containers", []):
                ctr_img_id = ctr.get("image_id") or ctr.get("ImageID") or ctr.get("Image", "")
                hash_prefix = img_hash[:12] if img_hash else ""
                if img_hash and (
                    ctr_img_id == img_hash or (hash_prefix and ctr_img_id.startswith(hash_prefix))
                ):
                    ctr_name = ctr.get("name") or ctr.get("Names", ["?"])[0]
                    in_use_by.append(ctr_name)
        except Exception as e:
            logger.debug("Could not fetch containers for in-use check: %s", e)

        if in_use_by:
            return f"Cannot delete '{display_name}': image is used by " + ", ".join(in_use_by)

        if not confirmed:
            return (
                f"Preview: would delete {display_name} ({size_str}).\n"
                f"Call delete_image(image_id={image_id!r}, confirmed=True) to confirm."
            )

        # Perform deletion using the resolved name+tag
        delete_name = repo
        delete_tag = img_tags[0] if img_tags else tag
        try:
            await client.request(
                "SYNO.Docker.Image",
                "delete",
                params={"name": delete_name, "tag": delete_tag},
            )
        except Exception as e:
            return f"Error deleting image '{display_name}': {e}"

        return f"Deleted {display_name} — {size_str} freed."

    @mcp.tool()
    async def check_image_updates(project_name: str | None = None) -> str:
        """Check for available image updates for a project or all images.

        Queries the local image list and reports which images have the
        'upgradable' flag set by the NAS registry check.

        Args:
            project_name: Optional project name to filter images.
                          If omitted, checks all locally available images.
        """
        try:
            data = await client.request(
                "SYNO.Docker.Image",
                "list",
                params={"limit": "-1", "offset": "0", "show_dsm": "false"},
            )
        except Exception as e:
            return f"Error listing images: {e}"

        images: list[dict[str, Any]] = data.get("images", [])
        if not images:
            return "No images found."

        if project_name:
            images = await _filter_images_for_project(client, project_name, images)
            if not images:
                return f"No images found for project '{project_name}'."
            header = f"Image update status for project '{project_name}':\n"
        else:
            header = f"Image update status (all {len(images)} images):\n"

        upgradable = [img for img in images if img.get("upgradable")]
        up_to_date = [img for img in images if not img.get("upgradable")]

        lines = [header]

        if upgradable:
            lines.append(f"Updates available ({len(upgradable)}):")
            for img in sorted(upgradable, key=lambda x: x.get("repository", "")):
                repo = img.get("repository", "?")
                tags = ", ".join(img.get("tags", []))
                size_mb = img.get("size", 0) // (1024 * 1024)
                lines.append(f"  {repo}:{tags}  ({size_mb} MiB)  ← UPDATE AVAILABLE")
            lines.append("")

        if up_to_date:
            lines.append(f"Up to date ({len(up_to_date)}):")
            for img in sorted(up_to_date, key=lambda x: x.get("repository", "")):
                repo = img.get("repository", "?")
                tags = ", ".join(img.get("tags", []))
                size_mb = img.get("size", 0) // (1024 * 1024)
                lines.append(f"  {repo}:{tags}  ({size_mb} MiB)")

        if not upgradable:
            lines.append("All images are up to date.")

        return "\n".join(lines)