import type { InterfaceRevisionId, MemberId, ValueType } from "../capability-model/types.js";
import { valueType } from "../capability-model/types.js";
import { QueryCompileError, type QueryArgument, type QueryUse } from "./types.js";

/** A row is an input membership, not a newly allocated Camino object. */
export type QueryRow =
  | {
      kind: "object";
      interfaceRevisionId: InterfaceRevisionId;
      membership?: { keyType?: "string" | "boolean" | "int64" };
    }
  | { kind: "pair"; source: QueryRow; target: QueryRow };

export type AggregateOperator = "count" | "countPresent" | "sum" | "avg" | "min" | "max";
export const aggregateOperators: readonly AggregateOperator[] = ["count", "countPresent", "sum", "avg", "min", "max"];

export function aggregateType(operator: AggregateOperator, input?: ValueType): ValueType {
  if (operator === "count") return valueType.uint64;
  const base = input?.kind === "optional" ? input.value : input;
  if (operator === "countPresent" && (base?.kind === "scalar" || base?.kind === "object-ref")) return valueType.uint64;
  if (base?.kind !== "scalar")
    throw new QueryCompileError("QUERY_AGGREGATE_TYPE", `${operator} requires a supported scalar operand`);
  const numeric = ["int32", "uint32", "int64", "uint64", "double"].includes(base.name);
  if ((operator === "min" || operator === "max") && (numeric || base.name === "string"))
    return valueType.optional(base);
  if (numeric && operator === "avg") return valueType.optional(valueType.double);
  if (numeric && operator === "sum")
    return valueType.optional(
      base.name === "double" ? valueType.double : base.name.startsWith("u") ? valueType.uint64 : valueType.int64,
    );
  throw new QueryCompileError("QUERY_AGGREGATE_TYPE", `${operator} does not accept ${base.name}`);
}

export function queryKeyType(type: ValueType): boolean {
  if (type.kind === "optional") return queryKeyType(type.value);
  return type.kind === "object-ref" || (type.kind === "scalar" && type.name !== "bytes");
}

/** Paths are resolved once by the compiler. Runtime never resolves authored names. */
export type QueryPathStep =
  | { kind: "source" | "target" }
  | {
      kind: "relation";
      interfaceRevisionId: InterfaceRevisionId;
      memberId: MemberId;
      targetInterfaceRevisionId: InterfaceRevisionId;
      optional: boolean;
    };
export interface QueryExpression {
  path: QueryPathStep[];
  leaf:
    | { kind: "field"; interfaceRevisionId: InterfaceRevisionId; memberId: MemberId }
    | { kind: "ref"; interfaceRevisionId: InterfaceRevisionId }
    | { kind: "entry" | "mapKey" };
  type: ValueType;
}
export interface QueryReduction {
  operator: AggregateOperator;
  operand?: QueryExpression;
  type: ValueType;
}
export type QueryPredicate =
  | { kind: "and" | "or"; children: QueryPredicate[] }
  | { kind: "not"; child: QueryPredicate }
  | {
      kind: "compare";
      expression: QueryExpression;
      operator: "eq" | "in" | "isNull" | "lt" | "lte" | "gt" | "gte";
      value: QueryArgument;
    }
  | {
      kind: "relation";
      path: QueryPathStep[];
      interfaceRevisionId: InterfaceRevisionId;
      memberId: MemberId;
      targetInterfaceRevisionId: InterfaceRevisionId;
      operator: "some" | "none" | "is" | "isNull";
      predicate?: QueryPredicate;
      value?: QueryArgument;
    }
  | {
      kind: "reduce";
      path: QueryPathStep[];
      interfaceRevisionId: InterfaceRevisionId;
      memberId: MemberId;
      targetInterfaceRevisionId: InterfaceRevisionId;
      where?: QueryPredicate;
      having: QueryAggregatePredicate;
    };
export type QueryAggregatePredicate =
  | { kind: "and" | "or"; children: QueryAggregatePredicate[] }
  | { kind: "not"; child: QueryAggregatePredicate }
  | {
      kind: "compare";
      expression: QueryExpression | QueryReduction;
      operator: "eq" | "in" | "isNull" | "lt" | "lte" | "gt" | "gte";
      value: QueryArgument;
    };
export interface QueryKey {
  path: string[];
  expression: QueryExpression;
}
export interface QueryRelationalStage {
  id: number;
  input?: number;
  row: QueryRow;
  operation:
    | {
        kind: "source";
        interfaceRevisionId: InterfaceRevisionId;
        memberId: MemberId;
        targetInterfaceRevisionId: InterfaceRevisionId;
      }
    | { kind: "filter"; predicate: QueryPredicate }
    | {
        kind: "expand";
        path: QueryPathStep[];
        interfaceRevisionId: InterfaceRevisionId;
        memberId: MemberId;
        targetInterfaceRevisionId: InterfaceRevisionId;
      }
    | { kind: "distinct"; keys: QueryKey[] };
}
export interface QueryRelationalTerminal {
  stage: number;
  path: string[];
  kind: "aggregate" | "groups";
  keys: QueryKey[];
  reductions: { path: string[]; reduction: QueryReduction }[];
  where?: QueryPredicate;
  having?: QueryAggregatePredicate;
  order: { expression: QueryExpression | QueryReduction; descending: boolean }[];
  first?: QueryArgument;
  all?: QueryArgument;
  after?: QueryArgument;
  /** Projection tree remains separate from the operator plan. */
  selection: import("./types.js").QuerySelection[];
  residual: boolean;
}
export interface QueryRelationalPlan {
  stages: QueryRelationalStage[];
  terminals: QueryRelationalTerminal[];
}
export type QueryEffectRecorder = (
  id: InterfaceRevisionId,
  name: string,
  use: QueryUse,
  node: import("graphql").ASTNode,
) => void;