import {
  GraphQLBoolean,
  GraphQLString,
  GraphQLInt,
  GraphQLFloat,
  GraphQLScalarType,
  GraphQLObjectType,
  GraphQLInputObjectType,
  GraphQLEnumType,
  GraphQLList,
  GraphQLNonNull,
  GraphQLSchema,
  GraphQLDirective,
  DirectiveLocation,
  specifiedDirectives,
  type GraphQLOutputType,
  type GraphQLInputType,
  type GraphQLFieldConfigMap,
  type GraphQLInputFieldConfigMap,
  type DocumentNode,
} from "graphql";
import { createHash } from "node:crypto";
import type {
  InterfaceRevision,
  InterfaceRevisionId,
  ValueType,
  RelationshipInterfaceMember,
} from "../capability-model/types.js";
import { QueryCompileError, type QueryDeclaration } from "./types.js";
import { relationalSchema, objectRow } from "./relational-schema.js";

// Validate losslessly; callers carry decimal strings across JSON transports.
function integerParser(name: string, min: bigint, max: bigint, value: unknown): string {
  if (
    typeof value !== "string" &&
    typeof value !== "bigint" &&
    !(typeof value === "number" && Number.isSafeInteger(value))
  )
    throw new Error(`${name} requires a canonical integer`);
  const text = String(value);
  if (!/^-?(0|[1-9][0-9]*)$/.test(text) || text === "-0") throw new Error(`${name} requires a canonical integer`);
  const n = BigInt(text);
  if (n < min || n > max) throw new Error(`${name} out of range`);
  return text;
}
const integerScalar = (name: string, min: bigint, max: bigint) => {
  const parse = (v: unknown) => integerParser(name, min, max, v);
  return new GraphQLScalarType({
    name,
    serialize: parse,
    parseValue: parse,
    parseLiteral(node) {
      if (node.kind !== "IntValue" && node.kind !== "StringValue") throw new Error(`${name} requires an integer`);
      return parse(node.value);
    },
  });
};
export const queryScalars = {
  bool: GraphQLBoolean,
  string: GraphQLString,
  int32: GraphQLInt,
  int64: integerScalar("Int64", -(1n << 63n), (1n << 63n) - 1n),
  uint32: integerScalar("UInt32", 0n, (1n << 32n) - 1n),
  uint64: integerScalar("UInt64", 0n, (1n << 64n) - 1n),
  double: GraphQLFloat,
  bytes: new GraphQLScalarType({ name: "Bytes" }),
};
export const cursorScalar = new GraphQLScalarType({
  name: "Cursor",
  parseValue(value) {
    if (typeof value !== "string" || value.length > 4096) throw new Error("Invalid cursor");
    return value;
  },
});

export function querySchema(
  declaration: QueryDeclaration,
  interfaces: readonly InterfaceRevision[],
  document?: DocumentNode,
) {
  const contracts = new Map(interfaces.map((entry) => [entry.revisionId, entry]));
  const objects = new Map<InterfaceRevisionId, GraphQLObjectType>();
  const orders = new Map<InterfaceRevisionId, GraphQLInputObjectType>();
  const byName = new Map<string, InterfaceRevision>();
  const comparisons = new Map<string, GraphQLInputObjectType>();
  const scalarTypes = new Map<string, ValueType>(
    Object.entries(queryScalars).map(([name, type]) => [type.name, { kind: "scalar", name } as ValueType]),
  );
  scalarTypes.set("Cursor", { kind: "scalar", name: "string" });
  const pageInfo = new GraphQLObjectType({
    name: "QxPageInfo",
    fields: {
      hasNextPage: { type: new GraphQLNonNull(GraphQLBoolean) },
      endCursor: { type: cursorScalar },
    },
  });
  const direction = new GraphQLEnumType({ name: "QxDirection", values: { ASC: {}, DESC: {} } });
  const contract = (id: InterfaceRevisionId) => {
    const found = contracts.get(id);
    if (!found || found.template) throw new QueryCompileError("QUERY_CONTRACT", `Expected closed interface ${id}`);
    return found;
  };
  const name = (id: InterfaceRevisionId) => {
    const revision = contract(id);
    const result =
      revision.displayName +
      (revision.application ? `_${createHash("sha256").update(id).digest("hex").slice(0, 12)}` : "");
    if (!/^[_A-Za-z][_0-9A-Za-z]*$/.test(result) || result.startsWith("__") || result.startsWith("Qx"))
      throw new QueryCompileError("QUERY_SCHEMA_NAME", `Unsupported query interface name ${result}`);
    const existing = byName.get(result);
    if (existing && existing.revisionId !== id)
      throw new QueryCompileError("QUERY_SCHEMA_NAME", `Conflicting query interface name ${result}`);
    byName.set(result, revision);
    return result;
  };
  const target = (member: RelationshipInterfaceMember): InterfaceRevisionId => {
    if (member.target.kind === "interface") return member.target.interfaceRevisionId;
    const atomId = member.target.atomId;
    const views = declaration.views.filter((entry) => entry.atomId === atomId);
    if (views.length !== 1)
      throw new QueryCompileError(
        "QUERY_VIEW_REQUIRED",
        `Declare exactly one interface view for ${member.target.atomId}`,
      );
    return views[0]!.interfaceRevisionId;
  };
  const scalar = (type: ValueType): GraphQLOutputType & GraphQLInputType => {
    if (type.kind === "optional") return scalar(type.value);
    if (type.kind !== "scalar")
      throw new QueryCompileError("QUERY_TYPE", "Only scalar/optional scalar query fields are supported");
    return queryScalars[type.name];
  };
  const comparison = (type: ValueType) => {
    const base = type.kind === "optional" ? type.value : type;
    const value = scalar(base);
    const key = String(value);
    let result = comparisons.get(key);
    if (!result) {
      const fields: GraphQLInputFieldConfigMap = { eq: { type: value }, isNull: { type: GraphQLBoolean } };
      if (base.kind === "scalar" && base.name !== "bytes")
        fields.in = { type: new GraphQLList(new GraphQLNonNull(value)) };
      if (base.kind === "scalar" && base.name !== "bool" && base.name !== "bytes")
        for (const op of ["lt", "lte", "gt", "gte"]) fields[op] = { type: value };
      result = new GraphQLInputObjectType({ name: `QxCompare${key}`, fields });
      comparisons.set(key, result);
    }
    return result;
  };
  const relational = relationalSchema(
    { contracts, target, name, scalar, comparison, scalarTypes, direction, cursor: cursorScalar, pageInfo },
    document,
  );
  relational.discover(declaration.root);
  const filter = (id: InterfaceRevisionId) => relational.where(objectRow(id));
  const order = (id: InterfaceRevisionId) => {
    let result = orders.get(id);
    if (!result) {
      const fields: GraphQLInputFieldConfigMap = {};
      for (const member of contract(id).members) {
        if (member.kind !== "value" || !member.queryRead) continue;
        const t = member.valueType.kind === "optional" ? member.valueType.value : member.valueType;
        if (t.kind === "scalar" && t.name !== "bytes") fields[member.displayName] = { type: direction };
      }
      if (Object.keys(fields).length === 0) return undefined;
      result = new GraphQLInputObjectType({ name: `${name(id)}Order`, fields });
      orders.set(id, result);
    }
    return result;
  };
  const object = (id: InterfaceRevisionId): GraphQLObjectType => {
    const existing = objects.get(id);
    if (existing) return existing;
    const result = new GraphQLObjectType({
      name: name(id),
      fields: () => {
        const helpers = relational.helpers(id);
        const metadata = new GraphQLObjectType({
          name: `QxMetadata_${name(id)}`,
          fields: {
            ref: { type: new GraphQLNonNull(relational.refs(id)) },
            ...(helpers ? { relations: { type: new GraphQLNonNull(helpers) } } : {}),
          },
        });
        const fields: GraphQLFieldConfigMap<unknown, unknown> = { _qx: { type: new GraphQLNonNull(metadata) } };
        for (const member of contract(id).members) {
          if (member.kind === "operation" || !member.queryRead) continue;
          if (!/^[_A-Za-z][_0-9A-Za-z]*$/.test(member.displayName) || member.displayName.startsWith("_"))
            throw new QueryCompileError("QUERY_SCHEMA_NAME", `Unsupported query field name ${member.displayName}`);
          if (member.kind === "value") {
            const type = scalar(member.valueType);
            fields[member.displayName] = {
              type: member.valueType.kind === "optional" ? type : new GraphQLNonNull(type),
            };
          } else {
            const targetId = target(member),
              node = object(targetId);
            if (member.cardinality === "exactly-one" || member.cardinality === "optional-one")
              fields[member.displayName] = {
                type: member.cardinality === "exactly-one" ? new GraphQLNonNull(node) : node,
              };
            else {
              const entry = new GraphQLObjectType({
                name: `${name(id)}_${member.displayName}_Entry`,
                fields: {
                  key: { type: new GraphQLNonNull(GraphQLString) },
                  ...(member.keyType
                    ? {
                        mapKey: {
                          type: new GraphQLNonNull(
                            queryScalars[member.keyType === "boolean" ? "bool" : member.keyType],
                          ),
                        },
                      }
                    : {}),
                  cursor: { type: cursorScalar },
                  node: { type: new GraphQLNonNull(node) },
                },
              });
              const connection = new GraphQLObjectType({
                name: `${name(id)}_${member.displayName}_Connection`,
                fields: {
                  entries: { type: new GraphQLNonNull(new GraphQLList(new GraphQLNonNull(entry))) },
                  pageInfo: { type: new GraphQLNonNull(pageInfo) },
                },
              });
              const ordering = order(targetId);
              fields[member.displayName] = {
                type: new GraphQLNonNull(connection),
                args: {
                  first: { type: GraphQLInt },
                  all: { type: GraphQLInt },
                  after: { type: cursorScalar },
                  where: { type: filter(targetId) },
                  ...(ordering ? { orderBy: { type: new GraphQLList(new GraphQLNonNull(ordering)) } } : {}),
                },
              };
            }
          }
        }
        return fields;
      },
    });
    objects.set(id, result);
    return result;
  };
  const schema = new GraphQLSchema({
    directives: [...specifiedDirectives, new GraphQLDirective({ name: "live", locations: [DirectiveLocation.FIELD] })],
    query: new GraphQLObjectType({
      name: "QxQuery",
      fields: { root: { type: new GraphQLNonNull(object(declaration.root)) } },
    }),
  });
  return { schema, byName, target, contracts, relational, scalarTypes };
}