How njprovk/creditscardtools works
1. Repository type and boundary
- This is a pure Python library, not an application or service.
- The runtime boundary is a small importable package, card_generator, whose public API is exposed through __init__.py.
2. Primary domain
- The library focuses on credit card number generation and validation.
- It supports common schemes such as Visa, MasterCard, Amex, and Discover, with generation constrained by card-brand rules and Luhn validity.
3. Core package layout
- card_generator/card_generator.py contains the generation logic.
- card_generator/card_validator.py contains the validation and lookup logic.
- card_generator/config.py likely centralizes shared constants or scheme/BIN configuration used by both subsystems.
4. Generation subsystem
- CardGenerator is the main abstraction for producing card records.
- It generates:
- the card number,
- an expiry date,
- a CVV,
- optional formatting for the card string,
- optional bank/BIN metadata.
- The generator appears to support multiple outputs per call via a count argument.
5. Validation subsystem
- CardValidator takes a card number and provides:
- Luhn check validity,
- card type detection,
- BIN-based metadata lookup.
- Validation is centered on static properties of the number rather than external verification.
6. Offline BIN data layer
- card_generator/bin-list-data.csv is a bundled local dataset used for BIN lookup.
- This is the main data boundary in the repository: generated or validated card numbers are mapped against this local file to derive brand, type, category, country, bank, and contact information.
- The README makes clear that no network access or API keys are needed at runtime.
7. Data flow across the library
- Input enters as a card scheme name or card number.
- Generation creates candidate numbers and applies checksum rules.
- Validation checks the number and, when possible, resolves BIN metadata from the CSV dataset.
- Optional metadata is attached to generated results only when the BIN is found locally.
8. Public API shape
- The package exports two main entry points:
- CardGenerator
- CardValidator
- The README examples suggest the API is intentionally small and predictable, with simple methods/properties rather than a large framework.
9. Testing boundary
- tests/test_card_generator.py and tests/test_card_validator.py cover the two main subsystems independently.
- This mirrors the architecture: generation and validation are separate concerns, each with its own behavior and invariants.
10. Packaging and dependency model
- pyproject.toml drives packaging and project metadata.
- The project emphasizes being dependency-free, so the architecture is intentionally lightweight and self-contained.
11. Quality and CI
- .github/workflows/ci.yml runs automated checks in GitHub Actions.
- .pre-commit-config.yaml and .flake8 indicate static quality gates are part of the workflow, supporting consistency for a small library codebase.
12. How to draw the architecture
- Draw the package as a single library box with two internal modules: generator and validator.
- Connect both modules to a shared local BIN CSV data source.
- Show the public API as a thin facade over these modules.
- Show tests and CI as separate quality/verification paths, not as runtime components.
Main entry points: __init__.py Public API · card_generator.py Generator · card_validator.py Validator · ci.yml CI workflow
Components 12
Runtime library
Importable package and core generation/validation logic.
- card_generator · Importable Python package exposing the library API.
card_generator - Public API · Thin export surface for the library's main classes.
card_generator/__init__.py - Generator · Produces card numbers and related card records.
card_generator/card_generator.py - Validator · Checks numbers, identifies card type, and resolves BIN metadata.
card_generator/card_validator.py - Config · Central configuration and scheme rules used by both subsystems.
card_generator/config.py
Local data
Bundled offline lookup data used by validation and metadata enrichment.
- BIN data · Bundled local BIN dataset for brand and issuer lookup.
card_generator/bin-list-data.csv
Verification
Tests and automated quality gates.
- Gen tests · Tests generation rules and output structure.
tests/test_card_generator.py - Val tests · Tests validation, lookup, and card type detection.
tests/test_card_validator.py - CI workflow · GitHub Actions workflow for automated checks.
.github/workflows/ci.yml - Quality gates · Pre-commit and linting rules that enforce code quality.
.pre-commit-config.yaml
Connections 14
- card_generator → Public API: exports · Package exposes the public classes through its top-level module.
- Public API → Generator: wraps · Public API surfaces the generator entry point.
- Public API → Validator: wraps · Public API surfaces the validator entry point.
- Generator → Config: uses · Generator consumes shared scheme and generation rules.
- Generator → BIN data: enriches · Generated card records can include issuer metadata from local BIN data.
- Validator → Config: uses · Validator relies on shared card rules and constants.
- Validator → BIN data: looks up · Validator resolves BIN-derived metadata from the bundled dataset.
- README → Public API: documents · README shows the intended small public API and usage flow.
- Packaging → card_generator: packages · Project metadata defines the installable library boundary.
- Gen tests → Generator: verifies · Unit tests cover generation behavior and invariants.
- Val tests → Validator: verifies · Unit tests cover validation and metadata lookup.
- CI workflow → Gen tests: runs · CI executes generator tests as part of the check pipeline.
- CI workflow → Val tests: runs · CI executes validator tests as part of the check pipeline.
- CI workflow → Quality gates: enforces · CI complements local lint and pre-commit quality gates.