/**
 * BI-P004 — ANALYTICS DATA CONTRACT.
 *
 * DoD: "Breaking dataset schema changes fail compatibility gate unless
 * explicitly versioned." Each breaking change class below is tested TWICE:
 * once under a minor bump (must be REFUSED) and once under a major bump (must
 * be ACCEPTED). A gate that only ever says yes, or only ever says no, would
 * pass a one-sided test; this one cannot.
 */
import { describe, it, expect } from 'vitest';
import {
  assertContractCompatible,
  checkContractCompatibility,
  contractHash,
  diffContracts,
  parseSemVer,
  validateContract,
  type DatasetContract,
} from '@/src/analytics/domain/contract';

function base(): DatasetContract {
  return {
    dataset_id: 'ds_vehicle_listings',
    version: '1.2.0',
    tier: 'CURATED',
    fields: [
      { name: 'listing_id', type: 'string', nullable: false, role: 'identifier', primary_identifier: true },
      { name: 'make', type: 'string', nullable: false, role: 'dimension' },
      { name: 'asking_price', type: 'int64', nullable: true, role: 'measure' },
      { name: 'listed_at', type: 'timestamp', nullable: false, role: 'attribute' },
    ],
    primary_identifiers: ['listing_id'],
    dimensions: ['make'],
    measures: ['asking_price'],
    freshness_slo_seconds: 3600,
    retention_days: 730,
    pii_classification: 'none',
    source_lineage: ['src_dealer_feed'],
    quality_rules: [
      { rule_id: 'qr_listing_id_unique', kind: 'unique', field_name: 'listing_id', severity: 'block' },
    ],
    allowed_purposes: ['market_analytics'],
  };
}

/** Apply a mutation and set the version. */
function next(mutate: (c: DatasetContract) => void, version: string): DatasetContract {
  const c: DatasetContract = JSON.parse(JSON.stringify(base()));
  mutate(c);
  c.version = version;
  return c;
}

const BREAKING_CASES: { name: string; mutate: (c: DatasetContract) => void; code: string }[] = [
  {
    name: 'field removed',
    mutate: (c) => {
      c.fields = c.fields.filter((f) => f.name !== 'make');
      c.dimensions = [];
    },
    code: 'field_removed',
  },
  {
    name: 'field type changed',
    mutate: (c) => {
      c.fields[2].type = 'float64';
    },
    code: 'field_type_changed',
  },
  {
    name: 'field became nullable',
    mutate: (c) => {
      c.fields[1].nullable = true;
    },
    code: 'field_became_nullable',
  },
  {
    name: 'field role changed',
    mutate: (c) => {
      c.fields[1].role = 'measure';
    },
    code: 'field_role_changed',
  },
  {
    name: 'required field added',
    mutate: (c) => {
      c.fields.push({ name: 'vat_rate', type: 'float64', nullable: false, role: 'attribute' });
    },
    code: 'required_field_added',
  },
  {
    name: 'primary identifier changed',
    mutate: (c) => {
      c.primary_identifiers = ['make'];
    },
    code: 'primary_identifier_changed',
  },
  {
    name: 'dimension removed',
    mutate: (c) => {
      c.dimensions = [];
    },
    code: 'dimension_removed',
  },
  {
    name: 'measure removed',
    mutate: (c) => {
      c.measures = [];
    },
    code: 'measure_removed',
  },
  {
    name: 'freshness SLO loosened',
    mutate: (c) => {
      c.freshness_slo_seconds = 86400;
    },
    code: 'freshness_slo_loosened',
  },
  {
    name: 'retention shortened',
    mutate: (c) => {
      c.retention_days = 30;
    },
    code: 'retention_shortened',
  },
  {
    name: 'allowed purpose removed',
    mutate: (c) => {
      c.allowed_purposes = [];
    },
    code: 'purpose_removed',
  },
  {
    name: 'PII classification raised',
    mutate: (c) => {
      c.pii_classification = 'personal';
    },
    code: 'pii_classification_raised',
  },
  {
    name: 'blocking quality rule removed',
    mutate: (c) => {
      c.quality_rules = [];
    },
    code: 'blocking_quality_rule_removed',
  },
  {
    name: 'blocking quality rule downgraded',
    mutate: (c) => {
      c.quality_rules[0].severity = 'warn';
    },
    code: 'blocking_quality_rule_downgraded',
  },
  {
    name: 'tier changed',
    mutate: (c) => {
      c.tier = 'SERVING';
    },
    code: 'tier_changed',
  },
];

describe('BI-P004 compatibility gate', () => {
  it.each(BREAKING_CASES)('REFUSES $name under a minor bump', ({ mutate, code }) => {
    const verdict = checkContractCompatibility(base(), next(mutate, '1.3.0'));
    expect(verdict.compatible).toBe(false);
    expect(verdict.breaking.map((b) => b.code)).toContain(code);
    expect(verdict.reason).toMatch(/MAJOR version bump/);
  });

  it.each(BREAKING_CASES)('ACCEPTS $name once explicitly versioned (major bump)', ({ mutate, code }) => {
    const verdict = checkContractCompatibility(base(), next(mutate, '2.0.0'));
    expect(verdict.compatible).toBe(true);
    expect(verdict.explicitly_versioned).toBe(true);
    expect(verdict.breaking.map((b) => b.code)).toContain(code);
  });

  it('a patch bump is equally refused — the gate is about the MAJOR, not about moving at all', () => {
    const verdict = checkContractCompatibility(
      base(),
      next((c) => c.fields.pop(), '1.2.1'),
    );
    expect(verdict.compatible).toBe(false);
  });

  it('allows genuinely additive changes without a major bump', () => {
    const additive = next((c) => {
      c.fields.push({ name: 'mileage_km', type: 'int64', nullable: true, role: 'measure' });
      c.measures.push('mileage_km');
      c.quality_rules.push({
        rule_id: 'qr_mileage_range',
        kind: 'range',
        field_name: 'mileage_km',
        severity: 'warn',
      });
      c.allowed_purposes.push('valuation');
      c.retention_days = 1095;
      c.freshness_slo_seconds = 1800;
    }, '1.3.0');
    const verdict = checkContractCompatibility(base(), additive);
    expect(verdict.compatible).toBe(true);
    expect(verdict.breaking).toEqual([]);
    expect(verdict.explicitly_versioned).toBe(false);
  });

  it('refuses a version that does not move forward', () => {
    expect(
      checkContractCompatibility(
        base(),
        next(() => {}, '1.2.0'),
      ).compatible,
    ).toBe(false);
    expect(
      checkContractCompatibility(
        base(),
        next(() => {}, '1.1.9'),
      ).compatible,
    ).toBe(false);
    expect(
      checkContractCompatibility(
        base(),
        next(() => {}, '0.9.0'),
      ).compatible,
    ).toBe(false);
  });

  it('treats date -> timestamp as a safe widening, and int64 -> float64 as NOT one', () => {
    const widened = next((c) => {
      c.fields.push({ name: 'sold_on', type: 'date', nullable: true, role: 'attribute' });
    }, '1.3.0');
    const later = JSON.parse(JSON.stringify(widened)) as DatasetContract;
    later.fields[later.fields.length - 1].type = 'timestamp';
    later.version = '1.4.0';
    expect(checkContractCompatibility(widened, later).compatible).toBe(true);

    const lossy = next((c) => {
      c.fields[2].type = 'float64';
    }, '1.3.0');
    expect(checkContractCompatibility(base(), lossy).compatible).toBe(false);
  });

  it('assertContractCompatible throws a CONFLICT rather than returning a verdict nobody reads', () => {
    expect(() =>
      assertContractCompatible(
        base(),
        next((c) => c.fields.pop(), '1.3.0'),
      ),
    ).toThrowError(/MAJOR/);
    expect(() =>
      assertContractCompatible(
        base(),
        next(() => {}, '1.3.0'),
      ),
    ).not.toThrow();
  });

  it('refuses to compare contracts for different datasets', () => {
    const other = next((c) => {
      c.dataset_id = 'ds_other';
    }, '1.3.0');
    expect(() => diffContracts(base(), other)).toThrowError(/SAME dataset/);
  });

  it('validateContract catches internally inconsistent contracts', () => {
    expect(() => validateContract(base())).not.toThrow();
    expect(() => validateContract({ ...base(), version: '1.2' })).toThrowError(/major.minor.patch/);
    expect(() => validateContract({ ...base(), fields: [] })).toThrowError(/no fields/);
    expect(() => validateContract({ ...base(), dimensions: ['nope'] })).toThrowError(/unknown field/);
    expect(() => validateContract({ ...base(), primary_identifiers: [] })).toThrowError(
      /no primary identifier/,
    );
    expect(() => validateContract({ ...base(), allowed_purposes: [] })).toThrowError(/allowed_purposes/);
    expect(() => validateContract({ ...base(), freshness_slo_seconds: 0 })).toThrowError(/freshness/);
    const dup = base();
    dup.fields.push({ ...dup.fields[0] });
    expect(() => validateContract(dup)).toThrowError(/duplicate field/);
  });

  it('contractHash is order-insensitive over fields but sensitive to meaning', () => {
    const a = base();
    const reordered = JSON.parse(JSON.stringify(a)) as DatasetContract;
    reordered.fields.reverse();
    expect(contractHash(reordered)).toBe(contractHash(a));

    const changed = JSON.parse(JSON.stringify(a)) as DatasetContract;
    changed.fields[1].nullable = true;
    expect(contractHash(changed)).not.toBe(contractHash(a));
  });

  it('parseSemVer rejects anything that is not major.minor.patch', () => {
    expect(parseSemVer('2.10.3')).toEqual({ major: 2, minor: 10, patch: 3 });
    for (const bad of ['v1.0.0', '1.0', '1.0.0-rc1', 'latest', '']) {
      expect(() => parseSemVer(bad)).toThrowError(/major.minor.patch/);
    }
  });
});