CLI app in pure safe Rust that converts a requested Steam Kazakhstan balance amount (KZT) into the RUB amount you need to pay a ggsel seller via SBP.

The app reads the current ggsel course from:

• product page (default): https://ggsel.net/catalog/product/avtopopolnenie-steam-kazaxstan-tenge-kzt-4841114
• fallback main page: https://ggsel.net/

• Pure Rust codebase (#![forbid(unsafe_code)])
• Zero Rust dependencies (std only)
• Runtime logging (--verbose)
• Structured error messages
• Automatic fallback from product page to main page when parser fails
• Offline mode for deterministic tests via --html-file

• Rust toolchain (cargo, rustc)
• curl in PATH (used to fetch HTTPS ggsel pages)

cargo build --release

# Live fetch from ggsel product page (with fallback to main page)
cargo run -- 1000

# Verbose logs
cargo run -- --verbose 1500

# Custom URLs
cargo run -- --url "https://ggsel.net/catalog/product/avtopopolnenie-steam-kazaxstan-tenge-kzt-4841114" --main-url "https://ggsel.net/" 2000

# Offline/fixture mode (no network)
cargo run -- --html-file tests/fixtures/product_page_sample.html 1000

Example output:

KZT requested: 1000.00
Detected rate: 1 KZT = 0.187000 RUB
RUB to pay via SBP: 187.00

--url <URL>           Primary ggsel URL
--main-url <URL>      Fallback ggsel URL
--timeout <SECONDS>   curl timeout in seconds
--html-file <PATH>    Read HTML from local file instead of network
--no-fallback         Do not fetch fallback URL if parser fails
-v, --verbose         Enable debug logs
-h, --help            Show help

cargo test

Tests include:

• unit tests for argument parsing
• unit tests for course extraction/parsing
• unit tests for conversion/rounding
• integration CLI tests with fixture HTML

• The converter rounds up to the nearest kopeck (0.01 RUB) to avoid underpaying.
• ggsel markup can change; if parsing fails, update the parser heuristics in src/parse.rs.