# Custom Ecto Types Refactor - Progress Tracker

## Overview

Implementing custom Ecto types to avoid "primitive obsession" by creating rich domain objects for IP addresses, email addresses, and MAC addresses. This follows the pattern from https://www.elixirstreams.com/tips/richer-domain-types-with-ecto-custom-types.

**Current Phase**: Phase 1 - IP Address Custom Type
**Status**: In Progress (1 of 7 schemas migrated)
**Started**: 2026-01-31

---

## Phase 1: IP Address Custom Type

### Completed ✅

1. **IPAddress Custom Type Implementation** (`lib/towerops/ecto_types/ip_address.ex`)
   - Implements `Ecto.Type` behavior with all 4 callbacks
   - Validates IPv4 and IPv6 addresses using `:inet.parse_address/1`
   - Provides helpers: `new/1`, `new!/1`, `ipv4?/1`, `ipv6?/1`, `to_string/1`, `to_tuple/1`
   - Handles edge cases:
     - nil values
     - IPv6 zone IDs (strips before validation)
     - CIDR notation (rejects)
     - BSD-style IP notation (accepts, matches Erlang behavior)
   - **JSON Encoding**: Added `@derive {Jason.Encoder, only: [:address]}` for GDPR data export compatibility
   - Database type: `:string` (no migrations needed)

2. **Comprehensive Unit Tests** (`test/towerops/ecto_types/ip_address_test.exs`)
   - 44 tests covering all callbacks and edge cases
   - Tests for: `type/0`, `cast/1`, `load/1`, `dump/1`, roundtrips, helpers
   - 100% coverage of custom type module
   - All tests passing ✅

3. **Schema Migration #1: Towerops.Admin.AuditLog**
   - File: `lib/towerops/admin/audit_log.ex`
   - Changed: `field :ip_address, :string` → `field :ip_address, Towerops.EctoTypes.IpAddress`
   - Risk Level: **Lowest** (append-only audit logs)
   - No validation code to remove (didn't have any)
   - Tests: All account data controller tests passing ✅
   - JSON serialization verified working for GDPR data export

4. **Documentation Updated**
   - Added "Custom Ecto Types" section to `CLAUDE.md` (after "Development Environment")
   - Includes: overview, available types, usage examples, implementation pattern, testing pattern
   - Plan file created at `/Users/graham/.claude/plans/swift-riding-mountain.md`

### In Progress 🔄

**Current Task**: Document remaining work before continuing

### Remaining Schemas to Migrate (6 schemas)

#### Low Risk (migrate next)

1. **Towerops.Accounts.BrowserSession** (`lib/towerops/accounts/browser_session.ex`)
   - Change: `field :ip_address, :string` → `field :ip_address, Towerops.EctoTypes.IpAddress`
   - Risk: Low (session tracking)
   - Notes: Keep `validate_length(:ip_address, max: 45)` if present (optional, harmless)
   - Tests to update: `test/towerops/accounts/browser_session_test.exs` (if exists)

2. **Towerops.Accounts.LoginAttempt** (`lib/towerops/accounts/login_attempt.ex`)
   - Change: `field :ip_address, :string` → `field :ip_address, Towerops.EctoTypes.IpAddress`
   - Risk: Low (logging only)
   - Tests to update: Check for related tests

#### Medium Risk (migrate after low risk)

3. **Towerops.Snmp.ArpEntry** (`lib/towerops/snmp/schemas/arp_entry.ex`)
   - Change: `field :ip_address, :string` → `field :ip_address, Towerops.EctoTypes.IpAddress`
   - Risk: Medium (SNMP discovery populates this)
   - Testing: Run SNMP discovery on test device after migration
   - Tests to update: `test/towerops/snmp/*_test.exs`

4. **Towerops.Snmp.Neighbor** (`lib/towerops/snmp/schemas/neighbor.ex`)
   - Change: `field :remote_address, :string` → `field :remote_address, Towerops.EctoTypes.IpAddress`
   - Risk: Medium (optional field, may be nil)
   - Note: Field name is `remote_address`, not `ip_address`
   - Tests to update: SNMP neighbor discovery tests

#### High Risk (migrate last)

5. **Towerops.Devices.Device** (`lib/towerops/devices/device.ex`) ⚠️ **HIGH RISK**
   - Change: `field :ip_address, :string` → `field :ip_address, Towerops.EctoTypes.IpAddress`
   - **Remove validation code** (lines 121-141 in current version):
     - `validate_ip_address/1` function
     - `parse_ip/1` function
     - Call to `|> validate_ip_address()` in changeset
   - Risk: High (core Device schema, heavily used)
   - Tests to update extensively: `test/towerops/devices_test.exs`
     - Add assertions: `assert %Towerops.EctoTypes.IpAddress{} = device.ip_address`
     - Verify: `assert device.ip_address.version == :ipv4`
     - Test invalid IP still produces changeset error
     - Test IPv6 addresses (lines 95-99 already exist)

6. **Towerops.Snmp.IpAddress** (`lib/towerops/snmp/schemas/ip_address.ex`) ⚠️ **COMPLEX**
   - Change: `field :ip_address, :string` → `field :ip_address, Towerops.EctoTypes.IpAddress`
   - **Keep**: `validate_prefix_length/1` (validates against `ip_type` field)
   - **Add**: Helper to auto-populate `ip_type` from `IPAddress.version`
   - Related fields: `ip_type`, `prefix_length`, `subnet_mask`
   - Future consideration: Could derive `ip_type` from `IPAddress.version` and remove redundant field
   - Risk: Complex (multiple related fields, SNMP-specific)

---

## Testing Strategy

### Per-Schema Testing Checklist

For each schema migration:
- [ ] Update schema field type
- [ ] Remove manual IP validation (if exists)
- [ ] Update related tests to assert on `%IpAddress{}` struct
- [ ] Run schema-specific tests: `mix test test/path/to/schema_test.exs`
- [ ] Run related integration tests
- [ ] Commit with message: `"Migrate [Schema] to IPAddress custom type"`

### Final Testing (after all 7 schemas)

- [ ] Run full test suite: `mix test`
- [ ] Check coverage: `mix test --cover` (target >90%)
- [ ] Run precommit checks: `mix precommit`
- [ ] Run Dialyzer: `mix dialyzer`
- [ ] Manual testing:
  - [ ] Device CRUD operations
  - [ ] SNMP discovery on test device
  - [ ] Audit log creation
  - [ ] GDPR data export

---

## Known Issues / Edge Cases Handled

1. **JSON Encoding**: Fixed by adding `@derive {Jason.Encoder, only: [:address]}` to IPAddress struct
   - Required for GDPR data export API (`/api/v1/account/data`)
   - Serializes as just the IP address string, not the full struct

2. **BSD-Style IP Notation**: `:inet.parse_address/1` accepts "192.168.1" as valid (interprets as "192.168.0.1")
   - This is expected Erlang behavior
   - Updated tests to document this, not reject it

3. **Database Compatibility**: No migrations needed
   - Column type stays as `varchar(45)`
   - Existing data valid on first load
   - Ecto handles conversion transparently via `load/1` callback

4. **IPv6 Zone IDs**: Stripped before validation (`fe80::1%eth0` → `fe80::1`)
   - Zone IDs are interface-specific and not stored

5. **CIDR Notation**: Rejected by custom type
   - Use separate `prefix_length` field instead
   - Prevents confusion between host addresses and network addresses

---

## Performance Considerations

- **Parsing Overhead**: ~1-5 microseconds per IP address (negligible)
- **Memory**: ~40 bytes per struct vs ~15-45 for string (~25 byte increase)
- **Query Performance**: Unchanged (database still stores strings)
- **JSON Serialization**: Efficient (only `address` field encoded)

---

## Rollback Plan

If issues arise after deployment:

1. Revert schema field changes to `:string` (git revert)
2. Restore `validate_ip_address/1` functions (git revert)
3. No database rollback needed (data unchanged, still stored as strings)
4. Redeploy previous version

---

## Future Phases (Not Started)

### Phase 2: Email Address Custom Type
- **Impact**: 4 schemas affected
- **Risk**: Medium (user-facing data)
- **Complexity**: Medium (normalization + case-insensitive handling)
- **Features**:
  - Normalize to lowercase
  - Split into local + domain parts
  - Consistent validation across schemas
- **Schemas**:
  - `Towerops.Accounts.User` (email field)
  - Others TBD (need to search codebase)

### Phase 3: MAC Address Custom Type
- **Impact**: 3 schemas affected
- **Risk**: Low (SNMP-specific)
- **Complexity**: Medium (multiple format handling)
- **Features**:
  - Handle multiple input formats (colon, hyphen, dot-separated)
  - Normalize to colon-separated lowercase
  - SNMP binary conversion support
- **Schemas**: TBD (need to search SNMP schemas)

### Phase 4: Optional Enhancements
- Derive `ip_type` from `IPAddress.version` in `Towerops.Snmp.IpAddress`
- Create `SubnetMask` custom type
- Create `IPNetwork` custom type (CIDR support)

---

## Commit History

1. `feat: add IPAddress custom Ecto type with comprehensive tests`
   - Created `lib/towerops/ecto_types/ip_address.ex`
   - Created `test/towerops/ecto_types/ip_address_test.exs`
   - Added Jason.Encoder derivation for JSON compatibility
   - All 44 tests passing

2. `docs: add Custom Ecto Types section to CLAUDE.md`
   - Added comprehensive documentation after "Development Environment" section
   - Includes pattern, usage examples, testing guidelines

3. `refactor: migrate AuditLog schema to IPAddress custom type`
   - Changed `field :ip_address, :string` → `field :ip_address, Towerops.EctoTypes.IpAddress`
   - No validation changes needed (schema didn't have IP validation)
   - All account data controller tests passing

---

## Next Steps

**When resuming this work:**

1. Continue with low-risk schemas (BrowserSession, LoginAttempt)
2. Move to medium-risk SNMP schemas (ArpEntry, Neighbor)
3. Carefully migrate high-risk Device schema with extensive testing
4. Complete complex IpAddress schema migration
5. Run full test suite and coverage check
6. Deploy to staging and monitor
7. Deploy to production

**Estimated Time Remaining**: 4-8 hours for Phase 1 completion

---

## Reference Files

**Pattern to Follow**:
- `lib/towerops/ecto_types/json_any.ex` - Existing custom type
- `test/towerops/ecto_types/json_any_test.exs` - Test pattern (184 lines)

**Modified Files** (so far):
- `lib/towerops/ecto_types/ip_address.ex` (NEW)
- `test/towerops/ecto_types/ip_address_test.exs` (NEW)
- `lib/towerops/admin/audit_log.ex` (MODIFIED)
- `CLAUDE.md` (MODIFIED - added Custom Ecto Types section)

**Files to Modify** (remaining):
- `lib/towerops/accounts/browser_session.ex`
- `lib/towerops/accounts/login_attempt.ex`
- `lib/towerops/snmp/schemas/arp_entry.ex`
- `lib/towerops/snmp/schemas/neighbor.ex`
- `lib/towerops/devices/device.ex` (HIGH RISK)
- `lib/towerops/snmp/schemas/ip_address.ex` (COMPLEX)

---

## Success Criteria for Phase 1 Completion

- [x] IPAddress custom type implemented with all 4 callbacks
- [x] >90% test coverage on custom type (100% achieved)
- [ ] All 7 schemas migrated successfully (1/7 complete)
- [ ] Duplicate validation code removed from changesets
- [ ] All existing tests pass
- [ ] No database migrations required (verified ✅)
- [x] Documentation updated in CLAUDE.md
- [ ] Code reviewed and deployed to production

**Progress**: 30% complete (foundation laid, 1 schema migrated, 6 remaining)
