"""Stage 7c — Multi-API executor.

Given a locked variant + filled slots, builds the request payloads for the main-screen API and
every touched sub-screen API, then fires them in dependency order.

For Stage 7 we MOCK the HTTP layer: the executor returns synthesized responses keyed off the
expected response schema, with success/error simulation paths so the eval suite can drive both.

Dependency rules (for the create flow):
  1. The MAIN screen save fires FIRST. Its response provides identity values (po_no,
     amendment_no) that sub-screen calls need.
  2. Sub-screen APIs fire AFTER main, in any order. Sub-screens that the user touched
     (any slot from that sub-screen is filled) OR that a pre-variant rule marked mandatory
     for the locked variant get fired.
  3. If any API errors, halt and surface the workbook-attached message.
"""
from __future__ import annotations

import time
import uuid
from dataclasses import asdict, dataclass, field
from typing import Any, Optional

from backend.agent.kb import JourneyKB


@dataclass
class PayloadField:
    api_property: str
    schema: str
    segment: str
    value: Any
    source_slot: Optional[str] = None       # which btsynonym provided the value
    source_kind: str = "user"               # user | default | derived | identity


@dataclass
class ApiCall:
    screen: str                             # ui_name owning this API
    api_file: str                           # e.g. CreatePO3.0.json
    endpoint: str                           # /CreatePO
    method: str                             # POST
    service_name: str
    role: str                               # save_submit (always for now)
    payload: dict[str, Any]                 # nested dict keyed by schema -> property
    field_records: list[PayloadField] = field(default_factory=list)
    # Filled in after firing:
    fired_at: Optional[float] = None
    success: Optional[bool] = None
    response: Optional[dict] = None
    error: Optional[dict] = None


@dataclass
class ExecutionResult:
    journey: str
    calls: list[ApiCall]
    success: bool
    error_summary: Optional[str] = None
    elapsed_ms: float = 0.0


# ============================================================================
# Payload assembly
# ============================================================================

def _resolve_value(
    journey_kb: JourneyKB,
    slots: dict[str, Any],
    api_property: str,
    api_data_item: str,
    schema: str,
) -> tuple[Any, Optional[str], str]:
    """Given the user's slots dict + an API field, return (value, source_btsynonym, source_kind).

    Search order:
      1. Direct match on data_item == btsynonym (lowercased).
      2. Alias-map lookup (slot_alias_map.json) for cross-name binding.
      3. Property name → snake-case match against btsynonyms.
      4. Default for context fields (ctxt_*, timestamps, GUIDs).
      Returns (None, None, "missing") if nothing matched."""
    di = (api_data_item or "").lower()
    if di in slots:
        return slots[di], di, "user"

    # Try alias-map
    alias_idx = journey_kb.alias_map.get("screens", [])
    for screen_aliases in alias_idx:
        for a in screen_aliases.get("aliases", []):
            if (a.get("api_property") == api_property
                    and (a.get("api_schema") or "").lower() == schema.lower()):
                bt = (a.get("btsynonym") or "").lower()
                if bt in slots:
                    return slots[bt], bt, "user"

    # Snake-case property fallback
    import re
    snake = re.sub(r"(?<!^)(?=[A-Z])", "_", api_property).lower()
    if snake in slots:
        return slots[snake], snake, "user"

    # Context / identity / time fields
    name_low = (api_property or "").lower()
    if name_low.startswith("ctxt") or "language" in name_low:
        return "EN", None, "default"
    if "guid" in name_low:
        return uuid.uuid4().hex, None, "derived"
    if "timestamp" in name_low or "createddate" in name_low or "lastmodifieddate" in name_low:
        return int(time.time()), None, "derived"
    if name_low in ("createdby", "lastmodifiedby"):
        return "ramco-chat", None, "default"

    return None, None, "missing"


def build_payload_for_api(
    journey_kb: JourneyKB,
    api_spec: dict,
    slots: dict[str, Any],
) -> tuple[dict[str, Any], list[PayloadField]]:
    """Walk the API's request_bindings and assemble a nested dict matching the request schema.

    The payload is shaped as `{schema: {segment: {property: value}}}` for header bindings and
    `{schema: [{property: value}, ...]}` for grid/details segments (which carry _grd_mseg).
    We keep it loose for now — the mock executor just inspects fields, not the exact shape.

    SKIP-sentinel handling: when the user explicitly declined to provide a value for a slot
    during the conversation, the resolver stores the SKIP sentinel in state. We must NEVER
    send the literal "__SKIP__" string to the API — strip the field instead so the API sees
    it as null/missing (which is what the user intended).
    """
    from backend.agent.state import is_skip
    payload_grouped: dict[str, dict[str, Any]] = {}
    records: list[PayloadField] = []
    for b in api_spec.get("request_bindings", []) or []:
        prop = b.get("property")
        di = b.get("data_item") or ""
        schema = b.get("schema") or "(unknown)"
        if not prop:
            continue
        val, src_slot, src_kind = _resolve_value(journey_kb, slots, prop, di, schema)
        if val is None and src_kind == "missing":
            # leave the field out of the payload (the API may treat missing as null)
            continue
        if is_skip(val):
            # user declined this slot — emit a trace-only record (source_kind=skipped_by_user)
            # so we keep an audit trail, but DON'T put it in the actual payload.
            records.append(PayloadField(
                api_property=prop, schema=schema, segment=b.get("segment") or "",
                value=None, source_slot=src_slot, source_kind="skipped_by_user",
            ))
            continue
        payload_grouped.setdefault(schema, {})[prop] = val
        records.append(PayloadField(
            api_property=prop, schema=schema, segment=b.get("segment") or "",
            value=val, source_slot=src_slot, source_kind=src_kind,
        ))
    return payload_grouped, records


# ============================================================================
# Mock HTTP layer
# ============================================================================

def _validate_against_master_data(slots: dict[str, Any], master_data: dict | None) -> dict | None:
    """If any user-provided slot value is NOT in its master_data table's valid_values list,
    return a mock error response. Otherwise return None to signal "all good, proceed".

    The error response includes a `valid_options_sample` — a short list of real, valid values
    the user can pick from. This is what powers the agent's "I couldn't find X. The valid
    suppliers are A, B, C — which would you like?" reply, plus the UI dropdown.
    """
    if not master_data:
        return None
    from backend.agent.state import is_skip
    tables = master_data.get("tables") or {}
    for slot_name, table in tables.items():
        v = slots.get(slot_name.lower())
        if v is None or is_skip(v):
            continue
        valid_values = list(table.get("valid_values") or [])
        valid_lower = {str(x).lower() for x in valid_values}
        if not valid_lower:
            continue
        if str(v).lower() not in valid_lower:
            tmpl = table.get("error_message") or "{value} is not valid for {slot}"
            try:
                msg = tmpl.format(value=v, slot=slot_name)
            except Exception:
                msg = f"{slot_name}={v}: {tmpl}"
            return {
                "ok": False,
                "error": {
                    "code": "MASTER_DATA_INVALID",
                    "slot": slot_name,
                    "value": v,
                    "message": msg,
                    # Top-N valid values so the agent can suggest + the UI can render a dropdown
                    "valid_options_sample": valid_values[:8],
                    "total_valid_count": len(valid_values),
                },
            }
    return None


def _mock_fire(call: ApiCall, master_data: dict | None = None, slots: dict[str, Any] | None = None) -> dict:
    """Simulated API response.

    If a `master_data_stub` is present for the journey, we validate every user-provided slot
    against it BEFORE pretending the API succeeded. A slot value not in its master-data list
    returns the Ramco-style error message verbatim — same as a real call would.

    For the main create call, success returns a synthetic po_no + amendment_no. For sub-screen
    calls, success returns ok.
    """
    # Master-data validation runs ONCE on the main call (the one that has the headline po_no
    # output). Sub-screens trust whatever the main call validated.
    name = call.api_file.lower()
    is_main_create = "createpo" in name

    if is_main_create and slots is not None:
        md_err = _validate_against_master_data(slots, master_data)
        if md_err is not None:
            return md_err

    if is_main_create:
        return {
            "ok": True,
            "po_no": f"PO/MOCK/{uuid.uuid4().hex[:6].upper()}",
            "amendment_no": 0,
            "ou_instance": 1001,
            "status": "FR",
        }
    if name.startswith("specify"):
        return {"ok": True}
    return {"ok": True}


# ============================================================================
# Main execution
# ============================================================================

def _touched_subscreens(journey_kb: JourneyKB, slots: dict[str, Any]) -> set[str]:
    """A sub-screen is 'touched' iff the user has filled a slot that BINDS to that sub-screen's
    save API (per Stage 4's slot_alias_map). Header fields like `buyerhdr` that appear visually
    on every sub-screen but bind to the main API DON'T touch those sub-screens.
    """
    # Map: api_file → ui_name (from api_map.json)
    api_to_ui: dict[str, str] = {}
    for s in journey_kb.api_map.get("screens") or []:
        for a in s.get("apis") or []:
            if a.get("role") == "save_submit":
                api_to_ui[a["api_file"]] = s["ui_name"]

    touched: set[str] = set()
    # Walk alias map for each filled slot; if the slot binds to a sub-screen's API, that
    # sub-screen is touched.
    filled = {k.lower() for k in slots.keys()}
    for screen_aliases in journey_kb.alias_map.get("screens") or []:
        for a in screen_aliases.get("aliases") or []:
            bt = (a.get("btsynonym") or "").lower()
            if bt not in filled:
                continue
            api_file = a.get("api_file")
            if not api_file:
                continue
            ui = api_to_ui.get(api_file)
            if ui and ui != journey_kb.main_screen_name:
                touched.add(ui)
    return touched


def execute(
    journey_kb: JourneyKB,
    slots: dict[str, Any],
    *,
    fire: bool = True,
    inject_error_on: Optional[str] = None,
) -> ExecutionResult:
    """Build and fire all required API calls for the locked variant.

    inject_error_on: ui_name of a sub-screen whose call should be simulated to fail (for testing)."""
    t0 = time.time()
    main_ui = journey_kb.main_screen_name
    save_apis = journey_kb.save_apis_by_screen

    calls: list[ApiCall] = []
    # 1) Main screen first
    if main_ui in save_apis:
        # Prefer the canonical "create" API (named like Create<...>)
        main_api_list = save_apis[main_ui]
        # Prefer api_file matching Create
        main_api = next(
            (a for a in main_api_list if "create" in a["api_file"].lower() and a["spec_version"] == "v3"),
            main_api_list[0],
        )
        payload, records = build_payload_for_api(journey_kb, main_api, slots)
        calls.append(ApiCall(
            screen=main_ui, api_file=main_api["api_file"], endpoint=main_api["endpoint"],
            method=main_api["method"], service_name=main_api["service_name"],
            role=main_api["role"], payload=payload, field_records=records,
        ))

    # 2) Sub-screens that were touched
    touched = _touched_subscreens(journey_kb, slots)
    for ui in sorted(touched):
        if ui not in save_apis:
            continue
        # Prefer the "Specify*" save_submit for the create flow
        specify_apis = [a for a in save_apis[ui] if "specify" in a["api_file"].lower()]
        sub_api = (specify_apis or save_apis[ui])[0]
        payload, records = build_payload_for_api(journey_kb, sub_api, slots)
        calls.append(ApiCall(
            screen=ui, api_file=sub_api["api_file"], endpoint=sub_api["endpoint"],
            method=sub_api["method"], service_name=sub_api["service_name"],
            role=sub_api["role"], payload=payload, field_records=records,
        ))

    # 3) Fire them
    success = True
    error_summary: Optional[str] = None
    if fire:
        for call in calls:
            call.fired_at = time.time()
            if inject_error_on == call.screen:
                call.success = False
                call.error = {"code": "MOCK_001", "message": f"Mock error on {call.screen}"}
                success = False
                error_summary = f"{call.screen}: {call.error['message']}"
                break
            call.response = _mock_fire(call, master_data=journey_kb.master_data, slots=slots)
            call.success = bool(call.response.get("ok"))
            if not call.success:
                success = False
                err = call.response.get("error") or {}
                err_msg = err.get("message") if isinstance(err, dict) else str(err)
                error_summary = f"{call.screen}: {err_msg or 'unknown error'}"
                break

    elapsed = (time.time() - t0) * 1000
    return ExecutionResult(
        journey=journey_kb.meta.activity_desc,
        calls=calls,
        success=success,
        error_summary=error_summary,
        elapsed_ms=elapsed,
    )


def execution_to_dict(result: ExecutionResult) -> dict:
    return {
        "journey": result.journey,
        "success": result.success,
        "error_summary": result.error_summary,
        "elapsed_ms": result.elapsed_ms,
        "call_count": len(result.calls),
        "calls": [
            {
                "screen": c.screen,
                "api_file": c.api_file,
                "endpoint": c.endpoint,
                "service_name": c.service_name,
                "method": c.method,
                "payload": c.payload,
                "field_count": len(c.field_records),
                "field_sources": {
                    "user": sum(1 for f in c.field_records if f.source_kind == "user"),
                    "default": sum(1 for f in c.field_records if f.source_kind == "default"),
                    "derived": sum(1 for f in c.field_records if f.source_kind == "derived"),
                },
                "fired_at": c.fired_at,
                "success": c.success,
                "response": c.response,
                "error": c.error,
            }
            for c in result.calls
        ],
    }