import { describe, it, expect } from "vitest";
import { Type, type TSchema } from "@alkdev/typebox";
import { typeCompat, type TypeCompatResult, type TypeMismatch } from "../../src/analysis/type-compat.js";

describe("typeCompat", () => {
  describe("exact match", () => {
    it("identical string schemas are compatible", () => {
      const result = typeCompat(Type.String(), Type.String());
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });

    it("identical number schemas are compatible", () => {
      const result = typeCompat(Type.Number(), Type.Number());
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });

    it("identical boolean schemas are compatible", () => {
      const result = typeCompat(Type.Boolean(), Type.Boolean());
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });

    it("identical object schemas are compatible", () => {
      const output = Type.Object({ name: Type.String(), age: Type.Number() });
      const input = Type.Object({ name: Type.String(), age: Type.Number() });
      const result = typeCompat(output, input);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });
  });

  describe("superset (output has extra fields)", () => {
    it("output with extra fields is still compatible", () => {
      const output = Type.Object({ name: Type.String(), age: Type.Number(), email: Type.String() });
      const input = Type.Object({ name: Type.String(), age: Type.Number() });
      const result = typeCompat(output, input);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
      expect(result!.detail).toBe("output has extra fields beyond input requirements");
    });

    it("output with many extra fields is compatible", () => {
      const output = Type.Object({ a: Type.String(), b: Type.Number(), c: Type.Boolean(), d: Type.String() });
      const input = Type.Object({ a: Type.String() });
      const result = typeCompat(output, input);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });
  });

  describe("subset (output missing required fields)", () => {
    it("output missing a required field is incompatible", () => {
      const output = Type.Object({ name: Type.String() });
      const input = Type.Object({ name: Type.String(), age: Type.Number() });
      const result = typeCompat(output, input);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
      expect(result!.mismatches).toBeDefined();
      expect(result!.mismatches!.length).toBeGreaterThan(0);
      const ageMismatch = result!.mismatches!.find((m) => m.path === "/age");
      expect(ageMismatch).toBeDefined();
      expect(ageMismatch!.expected).toBe("number");
      expect(ageMismatch!.actual).toBe("missing");
    });

    it("output missing multiple required fields reports all mismatches", () => {
      const output = Type.Object({ name: Type.String() });
      const input = Type.Object({ name: Type.String(), age: Type.Number(), email: Type.String() });
      const result = typeCompat(output, input);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
      const paths = result!.mismatches!.map((m) => m.path);
      expect(paths).toContain("/age");
      expect(paths).toContain("/email");
    });
  });

  describe("type mismatch", () => {
    it("string output vs number input is incompatible", () => {
      const output = Type.Object({ value: Type.String() });
      const input = Type.Object({ value: Type.Number() });
      const result = typeCompat(output, input);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
      const mismatch = result!.mismatches!.find((m) => m.path === "/value");
      expect(mismatch).toBeDefined();
      expect(mismatch!.expected).toBe("number");
      expect(mismatch!.actual).toBe("string");
    });

    it("boolean output vs string input is incompatible", () => {
      const output = Type.Object({ flag: Type.Boolean() });
      const input = Type.Object({ flag: Type.String() });
      const result = typeCompat(output, input);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
    });
  });

  describe("unknown passthrough", () => {
    it("output is Type.Unknown() returns undefined", () => {
      const result = typeCompat(Type.Unknown(), Type.String());
      expect(result).toBeUndefined();
    });

    it("input is Type.Unknown() returns undefined", () => {
      const result = typeCompat(Type.String(), Type.Unknown());
      expect(result).toBeUndefined();
    });

    it("both schemas are Type.Unknown() returns undefined", () => {
      const result = typeCompat(Type.Unknown(), Type.Unknown());
      expect(result).toBeUndefined();
    });
  });

  describe("nested objects (recursive)", () => {
    it("deeply nested objects with exact match are compatible", () => {
      const output = Type.Object({
        address: Type.Object({
          city: Type.String(),
          zip: Type.String(),
        }),
      });
      const input = Type.Object({
        address: Type.Object({
          city: Type.String(),
          zip: Type.String(),
        }),
      });
      const result = typeCompat(output, input);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });

    it("nested object with superset fields is compatible", () => {
      const output = Type.Object({
        address: Type.Object({
          city: Type.String(),
          zip: Type.String(),
          country: Type.String(),
        }),
      });
      const input = Type.Object({
        address: Type.Object({
          city: Type.String(),
          zip: Type.String(),
        }),
      });
      const result = typeCompat(output, input);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });

    it("nested object missing required field is incompatible", () => {
      const output = Type.Object({
        address: Type.Object({
          city: Type.String(),
        }),
      });
      const input = Type.Object({
        address: Type.Object({
          city: Type.String(),
          zip: Type.String(),
        }),
      });
      const result = typeCompat(output, input);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
      const mismatch = result!.mismatches!.find((m) => m.path === "/address/zip");
      expect(mismatch).toBeDefined();
    });

    it("nested object with type mismatch reports correct path", () => {
      const output = Type.Object({
        address: Type.Object({
          city: Type.Number(),
        }),
      });
      const input = Type.Object({
        address: Type.Object({
          city: Type.String(),
        }),
      });
      const result = typeCompat(output, input);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
      const mismatch = result!.mismatches!.find((m) => m.path === "/address/city");
      expect(mismatch).toBeDefined();
      expect(mismatch!.expected).toBe("string");
      expect(mismatch!.actual).toBe("number");
    });
  });

  describe("arrays", () => {
    it("identical array element types are compatible", () => {
      const result = typeCompat(Type.Array(Type.String()), Type.Array(Type.String()));
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });

    it("array with incompatible element types is not compatible", () => {
      const result = typeCompat(Type.Array(Type.Number()), Type.Array(Type.String()));
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
      expect(result!.mismatches!.length).toBeGreaterThan(0);
    });

    it("output array with union element type is not compatible with string array input", () => {
      const result = typeCompat(
        Type.Array(Type.Union([Type.String(), Type.Number()])),
        Type.Array(Type.String()),
      );
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
    });

    it("output array with string element is compatible with union array input", () => {
      const result = typeCompat(
        Type.Array(Type.String()),
        Type.Array(Type.Union([Type.String(), Type.Number()])),
      );
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });
  });

  describe("optional fields", () => {
    it("optional field in input that is present in output is compatible", () => {
      const output = Type.Object({ name: Type.String(), email: Type.String() });
      const input = Type.Object({ name: Type.String(), email: Type.Optional(Type.String()) });
      const result = typeCompat(output, input);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });

    it("optional field in input that is absent in output is compatible", () => {
      const output = Type.Object({ name: Type.String() });
      const input = Type.Object({ name: Type.String(), email: Type.Optional(Type.String()) });
      const result = typeCompat(output, input);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });

    it("required field in input that is absent in output is not compatible", () => {
      const output = Type.Object({ name: Type.String() });
      const input = Type.Object({ name: Type.String(), age: Type.Number() });
      const result = typeCompat(output, input);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
    });
  });

  describe("union types (subtype checking)", () => {
    it("string output is compatible with string|number input", () => {
      const result = typeCompat(Type.String(), Type.Union([Type.String(), Type.Number()]));
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });

    it("string|number output is NOT compatible with string input", () => {
      const result = typeCompat(Type.Union([Type.String(), Type.Number()]), Type.String());
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
    });

    it("number output is compatible with string|number input", () => {
      const result = typeCompat(Type.Number(), Type.Union([Type.String(), Type.Number()]));
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });

    it("literal output is compatible with matching union input", () => {
      const result = typeCompat(Type.Literal("hello"), Type.Union([Type.Literal("hello"), Type.Literal("world")]));
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });

    it("literal output is NOT compatible with non-matching union input", () => {
      const result = typeCompat(Type.Literal("other"), Type.Union([Type.Literal("hello"), Type.Literal("world")]));
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
    });
  });

  describe("literal types", () => {
    it("identical string literals are compatible", () => {
      const result = typeCompat(Type.Literal("hello"), Type.Literal("hello"));
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });

    it("different string literals are not compatible", () => {
      const result = typeCompat(Type.Literal("hello"), Type.Literal("world"));
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
    });

    it("string literal output is compatible with string input", () => {
      const result = typeCompat(Type.Literal("hello"), Type.String());
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });

    it("number literal output is compatible with number input", () => {
      const result = typeCompat(Type.Literal(42), Type.Number());
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });
  });

  describe("integer and number compatibility", () => {
    it("integer output is compatible with number input", () => {
      const result = typeCompat(Type.Integer(), Type.Number());
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });

    it("number output is NOT compatible with integer input", () => {
      const result = typeCompat(Type.Number(), Type.Integer());
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
    });
  });

  describe("complex realistic schemas", () => {
    it("realistic operation schemas - classify output compatible with enrich input", () => {
      const classifyOutput = Type.Object({
        categories: Type.Array(Type.String()),
        confidence: Type.Number(),
        metadata: Type.Optional(Type.Object({
          model: Type.String(),
          version: Type.String(),
        })),
      });
      const enrichInput = Type.Object({
        categories: Type.Array(Type.String()),
        confidence: Type.Number(),
      });
      const result = typeCompat(classifyOutput, enrichInput);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
    });

    it("realistic operation schemas - incompatible due to field type", () => {
      const fetchOutput = Type.Object({
        items: Type.Array(Type.Object({ id: Type.String(), name: Type.String() })),
        total: Type.Number(),
      });
      const processInput = Type.Object({
        items: Type.Array(Type.Object({ id: Type.Number(), name: Type.String() })),
        total: Type.Number(),
      });
      const result = typeCompat(fetchOutput, processInput);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
      const mismatch = result!.mismatches!.find((m) => m.path.includes("id"));
      expect(mismatch).toBeDefined();
    });

    it("multiple mismatches at different depths", () => {
      const output = Type.Object({
        name: Type.Number(),
        address: Type.Object({
          city: Type.Number(),
          zip: Type.Boolean(),
        }),
      });
      const input = Type.Object({
        name: Type.String(),
        address: Type.Object({
          city: Type.String(),
          zip: Type.String(),
        }),
      });
      const result = typeCompat(output, input);
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
      expect(result!.mismatches!.length).toBeGreaterThanOrEqual(3);
    });
  });

  describe("TypeCompatResult shape", () => {
    it("compatible result has no mismatches", () => {
      const result = typeCompat(Type.String(), Type.String());
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(true);
      expect(result!.mismatches).toBeUndefined();
    });

    it("incompatible result has mismatches array", () => {
      const result = typeCompat(Type.String(), Type.Number());
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
      expect(Array.isArray(result!.mismatches)).toBe(true);
      expect(result!.mismatches!.length).toBeGreaterThan(0);
    });

    it("TypeMismatch has correct shape", () => {
      const result = typeCompat(
        Type.Object({ value: Type.String() }),
        Type.Object({ value: Type.Number() }),
      );
      expect(result).toBeDefined();
      expect(result!.compatible).toBe(false);
      const mismatch: TypeMismatch = result!.mismatches![0]!;
      expect(typeof mismatch.path).toBe("string");
      expect(typeof mismatch.expected).toBe("string");
      expect(typeof mismatch.actual).toBe("string");
    });
  });
});