"""
silo_tree.py - Builds the Silo metadata tree in the FreeCAD document.

Reads silo/ entries from a .kc ZIP and creates a conditional hierarchy
of App::FeaturePython and App::DocumentObjectGroup objects in the
document tree.

Tree structure:
    Silo (App::DocumentObjectGroup)
    +-- Manifest          (always present)
    +-- Metadata          (if metadata.json is non-empty)
    +-- History           (if history.json has revisions)
    +-- Approvals         (if approvals.json has eco field)
    +-- Dependencies      (if dependencies.json has links)
    +-- Jobs              (group, if silo/jobs/ has YAML files)
    |   +-- default.yaml
    +-- Macros            (group, if silo/macros/ has .py files)
        +-- on_save
"""

import json
import zipfile

import FreeCAD

_SILO_GROUP_NAME = "Silo"

# Top-level silo/ entries with their object names, labels, and
# optional JSON field checks for conditional creation.
_KNOWN_ENTRIES = [
    # (zip_name, object_name, label, json_check)
    # json_check is None (always create) or (field_name, check_fn)
    ("silo/manifest.json", "SiloManifest", "Manifest", None),
    ("silo/metadata.json", "SiloMetadata", "Metadata", None),
    (
        "silo/history.json",
        "SiloHistory",
        "History",
        ("revisions", lambda v: isinstance(v, list) and len(v) > 0),
    ),
    (
        "silo/approvals.json",
        "SiloApprovals",
        "Approvals",
        ("eco", lambda v: v is not None),
    ),
    (
        "silo/dependencies.json",
        "SiloDependencies",
        "Dependencies",
        ("links", lambda v: isinstance(v, list) and len(v) > 0),
    ),
]


def _content_type(entry_name):
    """Determine content type from ZIP entry name."""
    if entry_name.endswith(".json"):
        return "json"
    if entry_name.endswith((".yaml", ".yml")):
        return "yaml"
    if entry_name.endswith(".py"):
        return "py"
    return "text"


def _decode(data):
    """Decode bytes to UTF-8 string, returning '' on failure."""
    try:
        return data.decode("utf-8")
    except Exception:
        return ""


def _should_create(data, json_check):
    """Check whether a conditional node should be created."""
    if json_check is None:
        return True
    field_name, check_fn = json_check
    try:
        parsed = json.loads(data)
        return check_fn(parsed.get(field_name))
    except Exception:
        return False


def _create_leaf(doc, parent, entry_name, data, obj_name, label):
    """Create one App::FeaturePython leaf and add it to parent group."""
    from silo_objects import SiloViewerObject
    from silo_viewproviders import SiloViewerViewProvider

    obj = doc.addObject("App::FeaturePython", obj_name)
    SiloViewerObject(obj)

    obj.SiloPath = entry_name
    obj.ContentType = _content_type(entry_name)
    obj.RawContent = _decode(data)
    obj.Label = label

    try:
        import FreeCADGui  # noqa: F401

        if obj.ViewObject is not None:
            SiloViewerViewProvider(obj.ViewObject)
    except ImportError:
        pass  # headless mode

    parent.addObject(obj)
    return obj


class SiloTreeBuilder:
    """Reads silo/ from a .kc ZIP and builds the document tree."""

    @staticmethod
    def read_silo_directory(filename):
        """Read silo/ entries from a .kc ZIP.

        Returns dict {entry_name: bytes}, e.g. {"silo/manifest.json": b"..."}.
        Returns {} on failure.
        """
        entries = {}
        try:
            with zipfile.ZipFile(filename, "r") as zf:
                for name in zf.namelist():
                    if name.startswith("silo/") and not name.endswith("/"):
                        entries[name] = zf.read(name)
        except Exception as exc:
            FreeCAD.Console.PrintWarning(
                f"silo_tree: could not read silo/ from {filename!r}: {exc}\n"
            )
        return entries

    @staticmethod
    def build_tree(doc, silo_contents):
        """Create the Silo group hierarchy in doc from silo/ entries."""
        if not silo_contents:
            return

        SiloTreeBuilder.remove_silo_tree(doc)

        root = doc.addObject("App::DocumentObjectGroup", _SILO_GROUP_NAME)
        root.Label = "Silo"

        # Top-level known entries (conditional creation)
        for zip_name, obj_name, label, json_check in _KNOWN_ENTRIES:
            if zip_name not in silo_contents:
                continue
            data = silo_contents[zip_name]
            if not _should_create(data, json_check):
                continue
            _create_leaf(doc, root, zip_name, data, obj_name, label)

        # Jobs subgroup
        job_entries = {
            k: v
            for k, v in silo_contents.items()
            if k.startswith("silo/jobs/") and not k.endswith("/")
        }
        if job_entries:
            jobs_group = doc.addObject("App::DocumentObjectGroup", "SiloJobs")
            jobs_group.Label = "Jobs"
            root.addObject(jobs_group)
            for entry_name in sorted(job_entries):
                basename = entry_name.split("/")[-1]
                safe_name = "SiloJob_" + basename.replace(".", "_").replace("-", "_")
                _create_leaf(
                    doc,
                    jobs_group,
                    entry_name,
                    job_entries[entry_name],
                    safe_name,
                    basename,
                )

        # Macros subgroup
        macro_entries = {
            k: v
            for k, v in silo_contents.items()
            if k.startswith("silo/macros/") and not k.endswith("/")
        }
        if macro_entries:
            macros_group = doc.addObject("App::DocumentObjectGroup", "SiloMacros")
            macros_group.Label = "Macros"
            root.addObject(macros_group)
            for entry_name in sorted(macro_entries):
                basename = entry_name.split("/")[-1]
                label = basename[:-3] if basename.endswith(".py") else basename
                safe_name = "SiloMacro_" + basename.replace(".", "_").replace("-", "_")
                _create_leaf(
                    doc,
                    macros_group,
                    entry_name,
                    macro_entries[entry_name],
                    safe_name,
                    label,
                )

        doc.recompute()
        FreeCAD.Console.PrintLog(
            f"silo_tree: built tree with {len(silo_contents)} entries in {doc.Name!r}\n"
        )

    @staticmethod
    def remove_silo_tree(doc):
        """Remove the Silo group and all descendants. Safe if absent."""
        root = doc.getObject(_SILO_GROUP_NAME)
        if root is None:
            return

        names = []

        def _collect(obj):
            if obj.Name in names:
                return
            names.append(obj.Name)
            if hasattr(obj, "OutList"):
                for child in obj.OutList:
                    _collect(child)

        _collect(root)

        for name in reversed(names):
            try:
                doc.removeObject(name)
            except Exception as exc:
                FreeCAD.Console.PrintWarning(
                    f"silo_tree: could not remove {name!r}: {exc}\n"
                )