"""Derive a web-form schema from a Langflow export.

Looks for form nodes — ``CustomInput*`` (``data.type`` or the inner
``display_name`` starting with ``CustomInput``, see
``backend/components/kirche/form_inputs.py``) plus user-built
``CustomComponent`` nodes whose display name ends with ``"Form"``
(e.g. ``Mitarbeiter Einstellen Form``) — and maps their ``template``
(minus ``code``) to ``{json_schema, ui_schema}`` for RJSF:

* ``name`` → property key (freely renamable in the Langflow code editor;
  kept verbatim so frontend payload keys match the runtime output —
  only empty names are skipped and collisions get a ``_2``/``_3`` suffix),
  ``display_name`` → ``title``,
  ``info`` → ``description``, ``value`` → ``default``,
  ``options`` → ``enum``, ``required`` → required array
* ``show: false`` fields are plumbing (e.g. the run envelope input), not
  form fields, and are skipped
* ``advanced`` fields render last via ``ui:order``
* ``_input_type`` → JSON type + widget (unknown types fall back to string
  so the parser never crashes on new fields)
* ``[visible_if ...]`` markers in ``info`` → conditional branches
  (``allOf`` with ``if``/``then`` per dependent field, arbitrarily nested;
  see ``_extract_visibility``). The marker is stripped from the shown
  description.

A flow without such a node gets ``{fallback: "textarea"}``: the frontend
renders one free-text box instead of a generated form.
"""

from __future__ import annotations

import re

#: ``[visible_if gebaeude=Kirche & bestandteil="Glocke, Orgel"]`` in a
#: field's ``info``. Authored in the Langflow code editor; the parser strips
#: the marker from the shown description and turns the conditions into
#: ``allOf``/``if``/``then`` branches (draft-07 — the ``dependencies``/
#: ``if`` keywords this stack's RJSF + ajv build honors; ``dependentSchemas``
#: is ignored there, so it is never emitted).
_VISIBLE_RE = re.compile(r"\[visible_if\s+([^\]]+)\]")


def _form_templates(langflow_json: dict) -> list[dict]:
    """Inner node dicts (``data.node``) of all form nodes."""
    if not isinstance(langflow_json, dict):
        return []
    data = langflow_json.get("data") or {}
    nodes = data.get("nodes") or []
    found = []
    for node in nodes:
        if not isinstance(node, dict):
            continue
        node_data = node.get("data") or {}
        node_type = str(node_data.get("type") or "")
        inner = node_data.get("node") or {}
        display = str(inner.get("display_name") or "")
        if node_type.startswith("CustomInput") or display.startswith("CustomInput"):
            found.append(inner)
        elif node_type == "CustomComponent" and display.endswith("Form"):
            # User-built form components (e.g. "Mitarbeiter Einstellen
            # Form"): same template contract, no kirche base needed.
            found.append(inner)
    return found


def _field_schema(name: str, field: dict) -> tuple[dict, dict]:
    """(JSON-Schema property, uiSchema entry) for one template field."""
    input_type = str(field.get("_input_type") or "")
    prop: dict = {}
    ui: dict = {}
    title = field.get("display_name") or name
    info = field.get("info") or ""
    if title:
        prop["title"] = title
    if info:
        prop["description"] = info

    options = field.get("options") or []
    if input_type in ("StrInput", "MessageTextInput"):
        prop["type"] = "string"
    elif input_type == "MultilineInput":
        prop["type"] = "string"
        ui["ui:widget"] = "textarea"
    elif input_type == "SecretStrInput":
        prop["type"] = "string"
        ui["ui:widget"] = "password"
    elif input_type == "IntInput":
        prop["type"] = "integer"
    elif input_type == "FloatInput":
        prop["type"] = "number"
    elif input_type == "BoolInput":
        prop["type"] = "boolean"
    elif input_type == "DropdownInput":
        prop["type"] = "string"
        if options:
            prop["enum"] = list(options)
    elif input_type == "MultiselectInput":
        prop["type"] = "array"
        items: dict = {"type": "string"}
        if options:
            items["enum"] = list(options)
        prop["items"] = items
        prop["uniqueItems"] = True
    elif input_type == "SliderInput":
        prop["type"] = "number"
        spec = field.get("range_spec") or {}
        if spec.get("min") is not None:
            prop["minimum"] = spec["min"]
        if spec.get("max") is not None:
            prop["maximum"] = spec["max"]
        if spec.get("step"):
            prop["multipleOf"] = spec["step"]
        ui["ui:widget"] = "range"
    elif input_type == "FileInput":
        # Stub for now: string reference only, real upload comes later.
        prop["type"] = "string"
    else:
        prop["type"] = "string"

    value = field.get("value")
    if value is not None:
        # Whitespace-only string values are the flow generator's sentinel
        # for "required, filled at runtime" (see make_flow_fixtures.py) —
        # not a real default for the web form.
        if isinstance(value, str) and not value.strip():
            return prop, ui
        # A default outside its enum would fail validation on touch.
        enum = prop.get("enum")
        if not (enum is not None and value not in enum):
            # bool is an int subclass; keep integer defaults clean.
            if prop.get("type") == "integer" and isinstance(value, bool):
                pass
            else:
                prop["default"] = value
    return prop, ui


def _split_conditions(text: str) -> list[str]:
    """Split ``a=X & b="Y Z"`` on ``&`` outside double quotes."""
    parts: list[str] = []
    buf: list[str] = []
    quoted = False
    for char in text:
        if char == '"':
            quoted = not quoted
            buf.append(char)
        elif char == "&" and not quoted:
            parts.append("".join(buf))
            buf = []
        else:
            buf.append(char)
    parts.append("".join(buf))
    return [part.strip() for part in parts if part.strip()]


def _parse_condition(token: str) -> tuple[str, object] | None:
    """``feld=Wert`` → ``(feld, wert)`` (bool/number coerced, quotes stripped)."""
    field, sep, value = token.partition("=")
    field, value = field.strip(), value.strip()
    if not sep or not field or not value:
        return None
    if len(value) >= 2 and value.startswith('"') and value.endswith('"'):
        value = value[1:-1]
    lowered = value.lower()
    if lowered == "true":
        return field, True
    if lowered == "false":
        return field, False
    try:
        return field, int(value)
    except ValueError:
        pass
    try:
        return field, float(value)
    except ValueError:
        pass
    return field, value


def _extract_visibility(info: str) -> tuple[str, list[tuple[str, object]]]:
    """(marker-free description, conditions) for a field's ``info`` text."""
    conditions: list[tuple[str, object]] = []

    def _collect(match: re.Match) -> str:
        for token in _split_conditions(match.group(1)):
            parsed = _parse_condition(token)
            if parsed is not None:
                conditions.append(parsed)
        return ""

    clean = _VISIBLE_RE.sub(_collect, info or "")
    clean = re.sub(r"\s+", " ", clean).strip()
    return clean, conditions


def _match_schema(trigger_field: dict, value: object) -> dict | None:
    """JSON-Schema fragment matching one condition, or None (unsupported)."""
    input_type = str(trigger_field.get("_input_type") or "")
    if input_type == "MultiselectInput":
        return {"contains": {"const": value}}
    if input_type == "BoolInput":
        return {"const": value} if isinstance(value, bool) else None
    if input_type in (
        "StrInput",
        "MessageTextInput",
        "MultilineInput",
        "SecretStrInput",
        "DropdownInput",
    ):
        return {"const": value} if isinstance(value, str) else None
    if input_type in ("IntInput", "FloatInput"):
        if isinstance(value, bool) or not isinstance(value, (int, float)):
            return None
        return {"const": value}
    return None


def _cyclic_fields(edges: dict[str, set[str]]) -> set[str]:
    """Fields on a trigger→dependent cycle (fail-open candidates)."""
    cyclic: set[str] = set()
    visiting: list[str] = []

    def _visit(node: str) -> None:
        visiting.append(node)
        for target in edges.get(node, ()):
            if target in visiting:
                cyclic.update(visiting[visiting.index(target) :])
            elif target not in cyclic:
                _visit(target)
        visiting.pop()

    for node in edges:
        if node not in cyclic:
            _visit(node)
    return cyclic


def extract_form_schema(langflow_json: dict) -> dict:
    """``{json_schema, ui_schema}``, or with ``fallback: "textarea"``."""
    templates = _form_templates(langflow_json)
    if not templates:
        return {
            "json_schema": {"type": "object", "properties": {}},
            "ui_schema": {},
            "fallback": "textarea",
        }
    template = templates[0].get("template") or {}
    # First pass: sanitize names (existing rules) and parse markers.
    records: list[dict] = []
    taken: set[str] = set()
    for key, field in template.items():
        if key == "code" or not isinstance(field, dict):
            continue
        if field.get("show") is False:
            continue
        raw_name = field.get("name") or key
        name = str(raw_name).strip()
        if not name:
            continue
        if name in taken:
            suffix = 2
            while f"{name}_{suffix}" in taken:
                suffix += 1
            name = f"{name}_{suffix}"
        taken.add(name)
        clean_info, conditions = _extract_visibility(str(field.get("info") or ""))
        records.append(
            {
                "name": name,
                "field": {**field, "info": clean_info},
                "required": bool(field.get("required")),
                "advanced": bool(field.get("advanced")),
                "conditions": conditions,
            }
        )
    by_name = {record["name"]: record for record in records}
    # Validate conditions: known trigger + supported match. Anything else
    # fails open (field stays always visible) so a stale marker can never
    # hide data or break validation.
    matches: dict[str, list[tuple[str, dict]]] = {}
    for record in records:
        resolved: list[tuple[str, dict]] = []
        for trigger, value in record["conditions"]:
            trigger_record = by_name.get(trigger)
            match = _match_schema(trigger_record["field"], value) if trigger_record else None
            if trigger_record is None or match is None or trigger == record["name"]:
                resolved = []
                break
            resolved.append((trigger, match))
        if resolved:
            matches[record["name"]] = resolved
    for name in _cyclic_fields(
        {name: {trigger for trigger, _ in conds} for name, conds in matches.items()}
    ):
        del matches[name]
    # Emit: conditional fields live only in their if/then branch (that is
    # what hides them in RJSF); everything else stays at root.
    properties: dict = {}
    required: list[str] = []
    ui_schema: dict = {}
    normal: list[str] = []
    advanced: list[str] = []
    for record in records:
        name = record["name"]
        prop, ui = _field_schema(name, record["field"])
        if name not in matches:
            properties[name] = prop
            if record["required"]:
                required.append(name)
        else:
            record["branch_prop"] = prop
        if ui:
            ui_schema[name] = ui
        (advanced if record["advanced"] else normal).append(name)
    json_schema: dict = {"type": "object", "properties": properties, "required": required}
    if matches:
        rules = []
        for name, conds in matches.items():
            record = by_name[name]
            rules.append(
                {
                    "if": {
                        "properties": {trigger: match for trigger, match in conds},
                        "required": [trigger for trigger, _ in conds],
                    },
                    "then": {
                        "properties": {name: record["branch_prop"]},
                        **({"required": [name]} if record["required"] else {}),
                    },
                }
            )
        json_schema["allOf"] = rules
        ui_schema["ui:order"] = normal + advanced + ["*"]
    elif advanced:
        ui_schema["ui:order"] = normal + advanced + ["*"]
    return {"json_schema": json_schema, "ui_schema": ui_schema}


def schema_field_names(cached: dict) -> list[str]:
    """All asked field names of a cached form schema (root + branches).

    Used for the run envelope's ``fields`` list so the runtime emits
    defaults only for asked fields. Order: root properties first, then
    branch discoveries.
    """
    if not isinstance(cached, dict):
        return []
    json_schema = cached.get("json_schema") or {}
    names: list[str] = []

    def _walk(node: object) -> None:
        if not isinstance(node, dict):
            return
        for subschema in (node.get("then"), node.get("else")):
            if isinstance(subschema, dict):
                for key in subschema.get("properties") or {}:
                    if key not in names:
                        names.append(key)
                _walk(subschema)
        for key in ("allOf", "oneOf", "anyOf"):
            items = node.get(key) or []
            if isinstance(items, list):
                for item in items:
                    _walk(item)

    for key in json_schema.get("properties") or {}:
        if key not in names:
            names.append(key)
    _walk(json_schema)
    return names