refactor: complete CLI-to-crate unification by consolidating export layer

- Move export functionality from CLI (src/main.rs) to library (src/export.rs)
- Remove 541 lines of duplicated export code from main.rs
- Reduce main.rs from ~1822 to ~1417 lines (22% reduction)
- CLI now uses library export functions: export_to_csv, export_to_gpx, export_to_event
- Enhance export_to_gpx with log_start_datetime parameter for accurate timestamps
- Remove unused structs: CsvExportOptions, CsvFieldMap from main.rs
- Update examples to use new export_to_gpx signature
- Update AGENTS.md to document full unification completion

Resolves issue #24: Complete CLI-to-Crate Unification

All tests pass (38 total):
- cargo clippy --all-targets --all-features -- -D warnings ✓
- cargo fmt --all -- --check ✓
- cargo test --verbose ✓ (38 passed)
- cargo test --features=cli --verbose ✓
- cargo build --release ✓ (no warnings)

Author: nerdCopter

AGENTS.md

@@ -13,15 +13,14 @@
 
 ## Architecture & Code Organization
 - **Library-first design:** Core logic in `src/lib.rs` and CLI entry point in `src/main.rs`.
-  - **Shared code:** Parser modules (`src/parser/`) are used by both library and CLI (`parse_frames`, `parse_headers_from_text`).
-  - **Duplicated code:** Export implementations exist separately in `src/export.rs` (library) and `src/main.rs` (CLI). CLI does NOT use library export functions.
-  - **Current state:** **Partial unification** — parsing shared, export duplicated (~1800 lines in `src/main.rs`).
+  - **Shared code:** Parser modules (`src/parser/`) and export functions (`src/export.rs`) are shared by both library and CLI.
+  - **CLI as thin wrapper:** The CLI (`src/main.rs`) uses library export functions (`export_to_csv`, `export_to_gpx`, `export_to_event`) with CLI-specific status messages.
+  - **Current state:** **Full unification complete** — parsing and export layers unified, CLI reduced from ~1800 to ~1400 lines.
 - **Decision criteria:** "Is this needed by crate consumers?" determines placement — shared logic in library, CLI-only logic in `src/main.rs`.
 - **Feature flags:** `csv`, `cli`, `json`, `serde` control optional dependencies; default: `csv` + `cli`.
 - **CRATE_USAGE.md reference:** See `CRATE_USAGE.md` for library API examples with feature flags.
-- **Code quality goals:** Reduce duplication by migrating CLI export logic to use library `export_to_csv()`, `export_to_gpx()`, `export_to_event()` functions.
 - **Testing:** Comprehensive tests distributed across `src/main.rs`, `src/conversion.rs`, `src/parser/stream.rs`, and `src/parser/helpers.rs`.
-- **Public API:** `parse_bbl_file()`, `parse_bbl_bytes()`, `BBLLog`, `ExportOptions`, conversion utilities, parser helpers.
+- **Public API:** `parse_bbl_file()`, `parse_bbl_bytes()`, `BBLLog`, `ExportOptions`, `export_to_csv()`, `export_to_gpx()`, `export_to_event()`, conversion utilities, parser helpers.
 
 ## Algorithms
 - **Method Selection:**  

examples/export_demo.rs

@@ -108,6 +108,7 @@ fn main() -> Result<()> {
             &log.gps_coordinates,
             &log.home_coordinates,
             &export_opts,
+            log.header.log_start_datetime.as_deref(),
         )?;
         println!("✓ GPX export complete");
     } else {

examples/gpx_export.rs

@@ -47,6 +47,7 @@ fn main() -> anyhow::Result<()> {
             &log.gps_coordinates,
             &log.home_coordinates,
             &export_opts,
+            log.header.log_start_datetime.as_deref(),
         )?;
         println!("✓ GPX export complete");
         println!("  Exported {} GPS coordinates", log.gps_coordinates.len());

examples/multi_export.rs

@@ -83,6 +83,7 @@ fn main() -> anyhow::Result<()> {
             &log.gps_coordinates,
             &log.home_coordinates,
             &export_opts,
+            log.header.log_start_datetime.as_deref(),
         )?;
         println!(
             "✓ GPX export complete ({} coordinates)",

src/export.rs

@@ -288,13 +288,23 @@ fn export_flight_data_to_csv(log: &BBLLog, output_path: &Path) -> Result<()> {
 }
 
 /// Export GPS data to GPX format
+///
+/// # Arguments
+/// * `input_path` - Path to the input BBL file (used for output naming)
+/// * `log_index` - Index of the current log (0-based)
+/// * `total_logs` - Total number of logs in the file
+/// * `gps_coordinates` - GPS coordinate data to export
+/// * `_home_coordinates` - Home coordinates (reserved for future use)
+/// * `export_options` - Export configuration options
+/// * `log_start_datetime` - Optional log start datetime from header for accurate timestamps
 pub fn export_to_gpx(
     input_path: &Path,
     log_index: usize,
     total_logs: usize,
     gps_coordinates: &[GpsCoordinate],
     _home_coordinates: &[GpsHomeCoordinate],
     export_options: &ExportOptions,
+    log_start_datetime: Option<&str>,
 ) -> Result<()> {
     if gps_coordinates.is_empty() {
         return Ok(());
@@ -339,19 +349,14 @@ pub fn export_to_gpx(
             }
         }
 
-        // Convert timestamp to ISO format
-        let total_seconds = coord.timestamp_us / 1_000_000;
-        let microseconds = coord.timestamp_us % 1_000_000;
-
-        // Use March 26, 2025 as base date
-        let hours = 5 + (total_seconds / 3600) % 24;
-        let minutes = (total_seconds % 3600) / 60;
-        let seconds = total_seconds % 60;
+        // Generate GPX timestamp from log_start_datetime + frame timestamp
+        // Following blackbox_decode approach: dateTime + (gpsFrameTime / 1000000)
+        let timestamp_str = generate_gpx_timestamp(log_start_datetime, coord.timestamp_us);
 
         writeln!(
             gpx_file,
-            r#"  <trkpt lat="{:.7}" lon="{:.7}"><ele>{:.2}</ele><time>2025-03-26T{:02}:{:02}:{:02}.{:06}Z</time></trkpt>"#,
-            coord.latitude, coord.longitude, coord.altitude, hours, minutes, seconds, microseconds
+            r#"  <trkpt lat="{:.7}" lon="{:.7}"><ele>{:.2}</ele><time>{}</time></trkpt>"#,
+            coord.latitude, coord.longitude, coord.altitude, timestamp_str
         )?;
     }