# Connection Strings Plan

This document tracks the plan for supporting multiple PostgreSQL connection string formats, converting between them, and mapping to/from a canonical model.

## Current Status (2025-08-30)

Implemented:
- Abstractions: `ConnStringFormat`, `HostEndpoint`, `ConnectionDescriptor`, `IConnectionStringCodec`, `IConnectionStringService`.
- Codecs:
  - `LibpqCodec` (libpq): parse/format; multi-host; `sslmode`, `application_name`, `connect_timeout`; quoting/escaping; preserves extras.
  - `NpgsqlCodec` (.NET/Npgsql): parse/format; alias recognition; multi-host with single or per-host ports; `SSL Mode`, `Application Name`, `Timeout`; double-quote rules; preserves extras.
- Tests for both codecs: parse, format, round-trip, edge quoting.

Not yet implemented:
- URL (postgresql://) codec ✓
- JDBC (jdbc:postgresql://) codec
- Composite `ConnectionStringService` (detect + convert) ✓
- Mapping helpers to/from `ServerConfiguration` ✓

## Updated Plan

1. Define canonical model and interfaces for connection strings. ✓
2. Establish normalization strategy for parameter aliases and extra `Properties` handling. ✓
3. Implement format-specific codecs:
   - libpq codec (parse/format; multi-host, quoting, sslmode, timeout, extras). ✓
   - Npgsql codec (parse/format; aliases, multi-host/ports, quoting, ssl mode, timeout, extras). ✓
   - URL (postgresql://) codec (parse/format; userinfo, host[:port], db, query params, percent-encoding). ✓
   - JDBC (jdbc:postgresql://) codec (parse/format; hosts, ports, db, properties; URL-like semantics).
4. Composite conversion service:
   - Implement `ConnectionStringService` composing codecs, detecting formats, converting via `ConnectionDescriptor`, and resolving alias priorities.
5. Mapping with application model:
   - Add mapping utilities between `ConnectionDescriptor` and `ServerConfiguration` (primary host/port, db, SSL mode), with sensible defaults.
6. Validation and UX:
   - Validation for malformed inputs & edge cases (mismatched host/port counts, invalid SSL mode, missing db/host, IPv6 bracket handling).
   - Ensure sensitive fields (password) are masked in logs/preview.
7. Tests:
   - Unit tests for URL and JDBC codecs; composite service detect/convert; mapping functions; cross-format round-trips; edge cases (spaces, quotes, unicode, IPv6, percent-encoding).
8. Documentation:
   - Keep this plan updated and enrich XML docs on codecs/service including alias mappings and quoting/escaping rules per format.

## Next Small Step

Implement the URL (postgresql://) codec with unit tests. Scope:
- Parse: `postgresql://[user[:password]@]host1[:port1][,hostN[:portN]]/[database]?param=value&...`
  - Support percent-decoding for user, password, database, and query values.
  - Handle IPv6 literals in `[::1]` form; allow multiple hosts with optional per-host ports.
  - Map common params: `sslmode`, `application_name`, `connect_timeout` and preserve other query params in `Properties`.
- Format: Build a URL using percent-encoding where required; emit multi-hosts and parameters from `Properties` not already emitted.
- Tests: basic parse/format, quoting/percent-encoding, multi-host with mixed ports, round-trips.

After that, implement the composite `ConnectionStringService` to detect/convert across libpq, Npgsql, and URL formats.