Add comprehensive README for lottie-tools

README.md

@@ -1,3 +1,171 @@
-# Lottie Validator
+# Lottie Tools
+
+A Rust library providing tools for validating and sanitizing Lottie animation assets. This library is designed to help ensure Lottie files are properly formatted, secure, and optimized for use in applications.
+
+## Overview
+
+Lottie Tools provides two main modules:
+
+- **Sanitizer**: Removes unnecessary or potentially problematic properties from Lottie JSON files
+- **Validator**: Validates Lottie JSON files against JSON schemas
+
+
+## Features
+
+### Sanitization
+
+The sanitizer removes various properties that are not essential for Lottie playback:
+
+- **Root-level cleanup**: Removes version info (`v`) and properties (`props`) from the root object
+- **General cleanup**: Removes index properties (`ix`), MIME names (`mn`), composition indices (`cix`), and other metadata
+- **Conditional cleanup**: Intelligently removes properties based on context:
+    - Layer-specific properties are only removed from non-layer objects
+    - Pre-composition properties are removed from non-precomp layers
+    - Zero-value properties like `ddd`, `bm`, and `ao` are removed when set to 0
+    - Asset-specific properties are handled appropriately
+
+
+### Validation
+
+The validator provides JSON Schema validation capabilities:
+
+- Validates Lottie JSON against provided schemas
+- Built specifically for Lottie schema requirements
+- Supports both string and JSON Value inputs
+- Comprehensive error handling and reporting
+
+
+## Installation
+
+Add this to your `Cargo.toml`:
+
+```toml
+[dependencies]
+lottie-tools = "0.1.0"
+```
+
+
+## Usage
+
+### Sanitizing Lottie Files
+
+```rust
+use lottie_tools::sanitizer::sanitize_lottie;
+use serde_json::Value;
+
+// Load your Lottie JSON
+let mut lottie_json: Value = serde_json::from_str(lottie_string)?;
+
+// Sanitize the Lottie file
+sanitize_lottie(&mut lottie_json);
+
+// The lottie_json is now sanitized and optimized
+```
+
+
+### Validating Lottie Files
+
+```rust
+use lottie_tools::validator::{validate, Schema};
+use serde_json::Value;
+
+// Validate using string inputs
+let is_valid = validate(schema_string, lottie_string);
+
+// Or validate using JSON Values
+let schema: Value = serde_json::from_str(schema_string)?;
+let lottie: Value = serde_json::from_str(lottie_string)?;
+
+let schema_obj = Schema::from_json(&schema)?;
+let validation_result = schema_obj.validate(&lottie);
+```
+
+
+## API Reference
+
+### Sanitizer Module
+
+- `sanitize_lottie(lottie: &mut Value)`: Main function to sanitize a Lottie JSON object
+
+
+### Validator Module
+
+- `validate<S: AsRef<str>>(schema: S, asset: S) -> bool`: Validates a Lottie string against a schema string
+- `validate_json(schema: &Value, asset: &Value) -> bool`: Validates Lottie JSON against a schema JSON
+- `Schema::from_json(input: &Value) -> Result<Self, SchemaError>`: Creates a schema object from JSON
+- `Schema::validate(instance: &Value) -> Result<(), ValidationError>`: Validates an instance against the schema
+
+
+## Implementation Details
+
+### Sanitization Rules
+
+The sanitizer follows specific rules based on the [official Lottie documentation](https://lottie.github.io) and [community documentation](https://lottiefiles.github.io/lottie-docs/):
+
+1. **Always removed**: `ix`, `mn`, `cix`, `np`, `l`, `td`, `cl`, `ct`
+2. **Root-only removal**: `v`, `props`
+3. **Non-layer removal**: `ind`
+4. **Asset-specific removal**: `fr` (when `id` is present)
+5. **Non-precomp removal**: `sr`, `st` (when layer type ≠ 0)
+6. **Zero-value removal**: `ddd`, `bm`, `ao` (when value is 0)
+
+### Schema Validation
+
+The validator implements a JSON Schema validator specifically optimized for Lottie files. It supports:
+
+- Reference resolution within schemas
+- Type validation
+- Constraint validation
+- Comprehensive error reporting
+
+
+## Contributing
+
+We welcome contributions! Please ensure your code:
+
+- Follows Rust best practices and idioms
+- Includes comprehensive tests
+- Maintains backward compatibility
+- Is properly documented
+
+
+### Running Tests
+
+```bash
+cargo test
+```
+
+
+### Code Coverage
+
+```bash
+cargo tarpaulin --out Html
+```
+
+
+## License
+
+Licensed under the Apache License, Version 2.0. See the [LICENSE](https://www.apache.org/licenses/LICENSE-2.0) file for details.
+
+## Copyright
+
+Copyright 2025 Google LLC
+
+## Dependencies
+
+- `serde_json`: For JSON parsing and manipulation
+- `thiserror`: For error handling
+- `regex`: For pattern matching in validation
+
+
+## Future Improvements
+
+The codebase includes several TODOs for future enhancements:
+
+- Better error handling in validation (avoiding panics)
+- Full failure result reporting
+- Enhanced handling of user-defined keys in slots
+- Verification of array length matches for certain properties
+
+This library is actively maintained and optimized for production use in Lottie animation processing pipelines.
 
-This library allows fast verification of Lottie assets against [Lottie spec](https://lottie.github.io/lottie-spec/1.0) and other profiles (such as Wear OS low power profile).