"""Kit manifest loading, slot inheritance, and which slots are worth showing."""

import os
import xml.etree.ElementTree as ET

import app_state

_dependency_cache = {}      # manifest path -> tuple of kit names it depends on


class MissingManifestError(Exception):
    """A kit the file needs has no manifest under the Sedona home folder.

    Raised rather than handled here, so the caller decides what to abandon: opening a
    file abandons the whole load, placing a palette component only abandons that
    component. Carrying the kit names lets either one name them in its own wording.
    """

    def __init__(self, kit_names, unresolved_type=None):
        self.kit_names = sorted(set(kit_names))
        self.unresolved_type = unresolved_type
        super().__init__(", ".join(self.kit_names))


def describe_missing_manifests(error):
    """The body of the dialog both callers show, pointing at the folder to check."""
    kit_list = "\n".join(f"    • {name}" for name in error.kit_names)
    home = app_state.SEDONA_HOME or "(not set)"

    lines = ["No manifest was found for:", "", kit_list, "", f"Sedona home folder:\n    {home}", ""]

    if error.unresolved_type:
        lines.append(
            f"Type '{error.unresolved_type}' inherits from a kit that is not in the "
            "file's schema block, so its slots cannot be resolved."
        )
        lines.append("")

    lines.append(
        "Check that the Sedona home folder is the right one and that it holds "
        "manifests/<kit>/<kit>-<checksum>.xml for each kit listed above. "
        "Preferences → Sedona home folder points it somewhere else."
    )
    return "\n".join(lines)


def read_kit_dependencies(kit_name, checksum=None):
    """The kits a manifest declares its kit was built against, by name only.

    A manifest lists them as <depend on="sys 1+"/>; the version bound is dropped here,
    since the schema block pins a build by checksum and has nowhere to record a range.

    An unreadable or absent manifest yields no dependencies rather than an error: the
    callers use this to widen a list, and a kit whose manifest is missing is already
    reported by whatever needed its types.
    """
    manifest_path = find_manifest_path(kit_name, checksum)
    if not manifest_path:
        return ()
    if manifest_path in _dependency_cache:
        return _dependency_cache[manifest_path]

    dependencies = []
    try:
        root = ET.parse(manifest_path).getroot()
        depends_element = root.find("depends")
        if depends_element is not None:
            for depend in depends_element.findall("depend"):
                on = (depend.get("on") or "").strip()
                if on:
                    dependencies.append(on.split()[0])
    except Exception as error:
        print(f"Cannot read dependencies of {manifest_path}: {error}")

    _dependency_cache[manifest_path] = tuple(dependencies)
    return _dependency_cache[manifest_path]


def read_summary_facet(slot_element):
    """Reads a slot's '@summary' facet. Absent means summary, matching manifest convention."""
    facets = slot_element.find("facets")
    if facets is None:
        return True
    for bool_facet in facets.findall("bool"):
        if bool_facet.get("name") == "summary":
            return (bool_facet.get("val", "true").strip().lower() != "false")
    return True


def read_all_facets(slot_element):
    """Every facet on a slot, as {name: value} with each one typed by its own tag.

    The manifest writes facets as <str name="unit" val="celsius"/>, <int name="max"
    val="1000"/> and so on, so the tag is the type. The Properties dialog needs the lot —
    unit, precision, min, max, trueText/falseText, range — and there are few enough of
    them per slot that carrying the whole dict costs less than a lookup per facet.
    """
    facets = {}
    facet_element = slot_element.find("facets")
    if facet_element is None:
        return facets

    for child in facet_element:
        name = child.get("name")
        if not name:
            continue
        raw = child.get("val", "")
        if child.tag == "bool":
            facets[name] = (raw.strip().lower() == "true")
        elif child.tag == "int":
            try:
                facets[name] = int(raw)
            except ValueError:
                facets[name] = raw
        elif child.tag in ("float", "double"):
            try:
                facets[name] = float(raw)
            except ValueError:
                facets[name] = raw
        else:
            facets[name] = raw
    return facets


def read_readonly_facet(slot_element):
    """Reads a slot's '@readonly' facet. Absent means writable."""
    facets = slot_element.find("facets")
    if facets is None:
        return False
    for bool_facet in facets.findall("bool"):
        if bool_facet.get("name") == "readonly":
            return (bool_facet.get("val", "false").strip().lower() == "true")
    return False


def get_slots_with_inheritance(type_name, kit_schemas):
    """Recursively resolves the slots for a given type by traversing its base chain."""
    if type_name not in kit_schemas:
        kit_prefix = type_name.split("::")[0] if "::" in type_name else type_name
        raise MissingManifestError([kit_prefix], unresolved_type=type_name)

    type_element = kit_schemas[type_name]
    base_type = type_element.get("base")

    resolved_slots = []
    if base_type:
        resolved_slots = get_slots_with_inheritance(base_type, kit_schemas)

    current_slots = []
    for slot in type_element.findall("slot"):
        current_slots.append({
            "name": slot.get("name"),
            "type": slot.get("type"),
            "default": slot.get("default"),   # absent means "the type's own zero"
            "flags": slot.get("flags", ""),
            "readonly": read_readonly_facet(slot),
            "summary": read_summary_facet(slot),
            "facets": read_all_facets(slot),
            "declared_id": int(slot.get("id"))
        })

    current_slots.sort(key=lambda s: s["declared_id"])
    resolved_slots.extend(current_slots)
    return resolved_slots


def compile_schema_registry(manifest_paths):
    """Loads and maps types across multiple kit files, ensuring all dependencies exist."""
    kit_schemas = {}

    for path in manifest_paths:
        try:
            tree = ET.parse(path)
            root = tree.getroot()
            kit_name = root.get("name")

            for type_tag in root.findall("type"):
                type_name = f"{kit_name}::{type_tag.get('name')}"
                kit_schemas[type_name] = type_tag
        except Exception as e:
            print(f"Error parsing manifest {path}: {e}")

    app_state.final_components_registry.clear()
    for type_name in kit_schemas.keys():
        flat_slots = get_slots_with_inheritance(type_name, kit_schemas)

        resolved_type_structure = []
        for sequence_id, slot_data in enumerate(flat_slots):
            resolved_type_structure.append({
                "slot_id": sequence_id,
                "name": slot_data["name"],
                "type": slot_data["type"],
                "default": slot_data["default"],
                "flags": slot_data["flags"],
                "readonly": slot_data["readonly"],
                "summary": slot_data["summary"],
                "facets": slot_data["facets"]
            })
        app_state.final_components_registry[type_name] = resolved_type_structure


def find_manifest_path(kit_name, checksum):
    """The manifest file describing a kit, or None when Sedona home holds none.

    A declared checksum is honoured when its file exists; otherwise the last manifest by
    filename is taken, the tolerance that lets a file with no checksums still open.
    """
    manifest_dir = os.path.join(app_state.SEDONA_HOME, "manifests", kit_name)

    if checksum:
        target_file = os.path.join(manifest_dir, f"{kit_name}-{checksum}.xml")
        if os.path.exists(target_file):
            return target_file

    if os.path.exists(manifest_dir):
        files = [
            f for f in os.listdir(manifest_dir)
            if f.startswith(f"{kit_name}-") and f.endswith(".xml")
        ]
        if files:
            files.sort()
            return os.path.join(manifest_dir, files[-1])

    return None


def resolve_truncated_checksum(kit_name, prefix):
    """The checksum of the one local manifest whose leading bytes match ``prefix``.

    Used when a device's schema reply cut a kit's checksum short. Returns the
    checksum as a signed 32-bit int (as read off the wire), or None when no
    manifest, or more than one, matches.
    """
    manifest_dir = os.path.join(app_state.SEDONA_HOME, "manifests", kit_name)
    if not os.path.isdir(manifest_dir):
        return None
    want = prefix.hex()
    matches = set()
    for f in os.listdir(manifest_dir):
        if f.startswith(f"{kit_name}-") and f.endswith(".xml"):
            hex_part = f[len(kit_name) + 1:-4].zfill(8).lower()
            if hex_part.startswith(want):
                matches.add(hex_part)
    if len(matches) != 1:
        return None
    value = int(matches.pop(), 16)
    return value - (1 << 32) if value & 0x80000000 else value


def find_manifest(kit_name, checksum):
    """Returns the parsed ET root of a kit manifest, or None."""
    checksum_hex = f"{checksum & 0xFFFFFFFF:08x}" if isinstance(checksum, int) else checksum
    path = find_manifest_path(kit_name, checksum_hex)
    if path is None:
        return None
    try:
        return ET.parse(path).getroot()
    except Exception:
        return None


def load_schema_kits_and_manifests():
    """Loads the manifests for the file's <schema> kits, plus any kit still only pending.

    A component placed from the palette records its kit in ``pending_schema_kits`` rather
    than writing to <schema> straight away — that reconciliation happens on save. Its
    types still have to resolve now, or the box could not be painted, so pending kits are
    compiled into the registry alongside the declared ones.
    """
    app_state.active_schema_kits.clear()
    if app_state.xml_root_element is None:
        return

    schema_elem = app_state.xml_root_element.find("schema")
    if schema_elem is None:
        return

    for kit in schema_elem.findall("kit"):
        name = kit.get("name")
        if name:
            app_state.active_schema_kits[name] = kit.get("checksum")

    kits_to_load = dict(app_state.active_schema_kits)
    for name, checksum in app_state.pending_schema_kits.items():
        kits_to_load.setdefault(name, checksum)

    manifest_paths = []
    missing_kits = []
    for name, checksum in kits_to_load.items():
        manifest_path = find_manifest_path(name, checksum)
        if manifest_path:
            manifest_paths.append(manifest_path)
        else:
            # Every missing kit is collected before reporting, so one dialog names them
            # all rather than the user fixing them one reopen at a time.
            missing_kits.append(name)

    if missing_kits:
        raise MissingManifestError(missing_kits)

    compile_schema_registry(manifest_paths)


def get_all_slots_for_type(type_str):
    """Returns every slot for a type as (name, type_string, flags, readonly) tuples."""
    if type_str not in app_state.final_components_registry:
        return []
    return [
        (slot["name"], slot["type"], slot["flags"], slot["readonly"])
        for slot in app_state.final_components_registry[type_str]
        if slot["name"]
    ]


def get_full_slots_for_type(type_str):
    """Every slot of a type, whole, in manifest order — nothing filtered out.

    get_slots_for_type hides most of them, which is right for a wiresheet box and wrong
    for the Properties dialog: a config slot is only editable somewhere, and this is
    that somewhere. Copies are handed out so a caller cannot edit the registry in place.
    """
    return [dict(slot) for slot in app_state.final_components_registry.get(type_str, [])
            if slot["name"]]


def get_slots_for_type(type_str, linked_slots=()):
    """
    Returns the slots worth painting for a given type, prefixed with double-digit
    index tags taken from the manifest so hidden rows leave gaps rather than renumber.

    Visibility, in order of precedence:
      - a linked slot is always shown, so its wire has a row to anchor to
      - '@summary false' hides the slot, even when it is runtime
      - runtime slots (no 'c' flag) are shown; they hold the live signal path
      - config slots that nothing links to are hidden as clutter
      - the 'o' (operator) flag hides a slot outright
    """
    if type_str not in app_state.final_components_registry:
        return []

    slots_list = []
    for slot_data in app_state.final_components_registry[type_str]:
        slot_name = slot_data["name"]
        if not slot_name:
            continue
        if "o" in slot_data["flags"]:
            continue

        is_linked = slot_name in linked_slots
        if not is_linked:
            if not slot_data.get("summary", True):
                continue
            if "c" in slot_data["flags"]:
                continue

        # Format to double digits (e.g., 00, 01, 02)
        padded_id = f"{slot_data['slot_id']:02d}"
        display_label = f"{padded_id}. {slot_name}"

        # Keep structural name unchanged for XML lookup inside comp, but pass display label
        slots_list.append((slot_name, display_label))

    return slots_list