"""Compatibility shim over the versioned manual projection boundary."""

from __future__ import annotations

import hashlib
import json
from dataclasses import dataclass
from importlib.metadata import version
from pathlib import Path
from typing import Protocol

from .errors import DocForgeError
from .manual_projection import build_manual_projection_package, build_manual_render_plan
from .models import ProjectSnapshot, RenderView


@dataclass(frozen=True)
class PreparedRender:
    render_identity: str
    output_hash: str
    output: bytes
    renderer: str
    renderer_version: str
    template_hash: str


class Renderer(Protocol):
    """Fixed interface implemented by explicitly registered built-in renderers."""

    renderer_id: str
    renderer_version: str

    def prepare(
        self,
        snapshot: ProjectSnapshot,
        view: RenderView,
        template_bytes: bytes,
        *,
        changeset_hash: str | None,
    ) -> PreparedRender: ...


class GenericHtmlRenderer:
    """Preserve the public v1 renderer API over the plan-only manual renderer."""

    renderer_id = "generic_html"
    contract_version = "1"

    def __init__(self) -> None:
        self.renderer_version = (
            f"{self.contract_version}+markdown-it-py-{version('markdown-it-py')}"
        )

    def prepare(
        self,
        snapshot: ProjectSnapshot,
        view: RenderView,
        template_bytes: bytes,
        *,
        changeset_hash: str | None,
    ) -> PreparedRender:
        selected = tuple(
            node for node in snapshot.nodes if not view.families or node.family in view.families
        )
        selected_ids = {node.node_id for node in selected}
        selected_edges = tuple(
            edge
            for edge in snapshot.edges
            if edge.source_id in selected_ids and edge.target_id in selected_ids
        )
        template_hash = hashlib.sha256(template_bytes).hexdigest()
        identity_payload = {
            "schema_version": 1,
            "project_id": snapshot.descriptor.project_id,
            "adapter": snapshot.descriptor.adapter,
            "source_hash": snapshot.source_hash,
            "changeset_hash": changeset_hash,
            "renderer": self.renderer_id,
            "renderer_version": self.renderer_version,
            "view": {
                "id": view.view_id,
                "title": view.title,
                "families": list(view.families),
                "output": view.output_path.relative_to(snapshot.descriptor.root).as_posix(),
            },
            "template_hash": template_hash,
            "nodes": [
                {
                    "id": node.node_id,
                    "content_hash": node.content_hash,
                    "source_path": node.source_path,
                }
                for node in selected
            ],
            "edges": [edge.as_dict() for edge in selected_edges],
        }
        render_identity = hashlib.sha256(
            json.dumps(identity_payload, sort_keys=True, separators=(",", ":")).encode("utf-8")
        ).hexdigest()
        plan = build_manual_render_plan(snapshot, view, changeset_hash=changeset_hash)
        package = build_manual_projection_package(
            plan,
            template_bytes,
            renderer_id=self.renderer_id,
            renderer_version=self.renderer_version,
            max_output_bytes=snapshot.descriptor.limits.max_render_bytes,
        )
        from docforge_renderers.manual import ManualHtmlRenderer

        result = ManualHtmlRenderer(self.renderer_version).render(
            package,
            render_identity=render_identity,
        )
        if len(result.artifacts) != 1:
            raise DocForgeError(
                "invalid_projection",
                "Manual renderer returned an unsupported artifact set",
            )
        output = result.artifacts[0].content
        return PreparedRender(
            render_identity=render_identity,
            output_hash=hashlib.sha256(output).hexdigest(),
            output=output,
            renderer=self.renderer_id,
            renderer_version=self.renderer_version,
            template_hash=template_hash,
        )


_RENDERERS: dict[str, type[GenericHtmlRenderer]] = {
    GenericHtmlRenderer.renderer_id: GenericHtmlRenderer
}


def renderer_for(view: RenderView) -> Renderer:
    factory = _RENDERERS.get(view.renderer)
    if factory is None:
        raise DocForgeError(
            "unsupported_renderer", "View does not name a supported built-in renderer"
        )
    return factory()


def relative_output(snapshot: ProjectSnapshot, path: Path) -> str:
    return path.relative_to(snapshot.descriptor.root).as_posix()