122 lines
4.0 KiB
Markdown
122 lines
4.0 KiB
Markdown
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# Weather Parser Documentation
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## Overview
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The weather parser module provides parsing capabilities for aviation weather reports including METAR, SPECI, and TAF messages. It is integrated into the system using a composite parser pattern that routes weather reports to the weather parser while maintaining backward compatibility with existing aviation telegram parsing.
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## Architecture
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The weather parser follows Clean Architecture principles:
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- **Domain Layer** (`internal/domain/weather/`): Core domain types and interfaces
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- **Port Layer** (`internal/port/weather_parser.go`): Parser interface definition
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- **Adapter Layer** (`internal/adapter/parser/weather/`): Parser implementation
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- **Composite Parser** (`internal/adapter/parser/composite.go`): Routes messages to appropriate parser
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## Supported Report Types
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### METAR (Aviation Routine Weather Report)
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Standard hourly weather observations from airports.
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**Example:**
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```
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METAR KJFK 251200Z 35012KT 10SM FEW020 25/18 Q1013=
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```
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### SPECI (Aviation Selected Special Weather Report)
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Special weather observations issued when conditions change significantly.
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**Example:**
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```
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SPECI KORD 251215Z 27015G25KT 5SM -RA BKN030 OVC050 20/18 A2992=
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```
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### TAF (Terminal Aerodrome Forecast)
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Forecast weather conditions for airports, typically valid for 24-30 hours.
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**Example:**
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```
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TAF KJFK 251200Z 2512/2612 35012KT 10SM FEW020 FM251800 36015KT 10SM SCT030=
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```
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## Parsed Elements
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### Core Elements
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- **Station**: 4-letter ICAO airport code
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- **Time**: Issue/observation time (DDHHmmZ format)
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- **Wind**: Direction, speed, gusts, variable conditions
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- **Visibility**: Distance, unit (meters or statute miles), directional visibility
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- **Clouds**: Type (FEW/SCT/BKN/OVC/VV), altitude, modifiers (CB/TCU)
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- **Temperature/Dewpoint**: Temperature in Celsius
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- **Altimeter**: Pressure setting (QNH in hPa or A in inHg)
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- **Weather Phenomena**: Intensity, descriptors, weather codes
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### TAF-Specific Elements
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- **Validity Period**: Forecast valid from/to times
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- **Periods**: Main forecast, FM (from), TEMPO (temporary), BECMG (becoming)
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- **Probability**: PROB30, PROB40 for uncertain conditions
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## Error Handling
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The parser uses a lenient approach:
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- **Unrecognized tokens**: Recorded in `warnings` array, parsing continues
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- **Missing required fields**: Returns appropriate domain errors
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- **Invalid format**: Returns `ErrInvalidFormat`
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This ensures that partial parsing is possible even when some elements are not recognized.
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## Usage
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The weather parser is automatically integrated via the composite parser. No special configuration is required.
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### Message Flow
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1. Raw message received
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2. Composite parser checks if message is a weather report
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3. If weather report: parsed by weather parser
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4. If not: parsed by aviation parser (existing behavior)
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5. Parsed result stored in `telegrams` table with `category` = "METAR"/"SPECI"/"TAF"
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6. Structured data stored in `body_data` JSONB field
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### Database Storage
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Weather reports are stored in the existing `telegrams` table:
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- `category`: "METAR", "SPECI", or "TAF"
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- `body_data`: JSONB containing structured weather data
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- `content`: Original raw text
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- `message_id`: Generated as `{station}-{issue_time}`
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## Testing
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Test files are located in `internal/adapter/parser/weather/`:
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- `classifier_test.go`: Tests report type classification
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- `metar_parser_test.go`: Tests METAR/SPECI parsing
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- `taf_parser_test.go`: Tests TAF parsing
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- `composite_test.go`: Tests composite parser routing
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Run tests:
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```bash
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go test ./internal/adapter/parser/weather/... -v
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```
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## Limitations and Future Enhancements
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Current implementation covers core METAR/TAF elements. Future enhancements may include:
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- Runway Visual Range (RVR) parsing
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- More comprehensive weather phenomenon codes
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- Enhanced TAF period parsing
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- Additional METAR modifiers
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- Station metadata integration
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## References
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- [ICAO Annex 3: Meteorological Service for International Air Navigation](https://www.icao.int/safety/meteorology/pages/annex-3.aspx)
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- [WMO Manual on Codes](https://library.wmo.int/index.php?lvl=notice_display&id=13617)
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