inkhaven 1.7.0

//! LING-1 L-P2 — `inkhaven language metrics <lang>`: deterministic quantitative
//! metrics over a language's lexicon + phonology (entropy, Zipf fit, phonotactic
//! saturation, mora weight). The information-theoretic complement to
//! `language stats` (descriptive counts). Read-only; `--json` for machine use.

use std::path::Path;

use crate::conlang::metrics::LanguageMetrics;
use crate::error::{Error, Result};

use super::*;

pub(crate) fn metrics(project: &Path, language: &str, json: bool) -> Result<()> {
    let (store, hierarchy, lang_book) = open_lang_book(project, language)?;
    let phon = load_phonology(&store, &hierarchy, &lang_book)?.unwrap_or_default();
    let entries = load_dictionary(&store, &hierarchy, &lang_book)?;
    let m = crate::conlang::metrics::metrics(&phon, &entries);

    if json {
        println!(
            "{}",
            serde_json::to_string_pretty(&m)
                .map_err(|e| Error::Store(format!("serializing metrics: {e}")))?
        );
        return Ok(());
    }

    print_report(language, &m);
    Ok(())
}

fn print_report(language: &str, m: &LanguageMetrics) {
    println!("language metrics · {language}");
    if m.analyzable_words == 0 {
        println!("  (no analyzable words — add dictionary entries that parse as the language's phonemes)");
        return;
    }
    println!(
        "  corpus    · {} analyzable word(s), {} segments",
        m.analyzable_words, m.total_segments
    );
    println!(
        "  entropy   · {:.2} bits (max {:.2}) · evenness {:.0}% · perplexity {:.1}",
        m.phoneme_entropy,
        m.phoneme_entropy_max,
        m.phoneme_evenness * 100.0,
        m.phoneme_perplexity,
    );
    println!(
        "  zipf      · slope {:.2} (≈−1 is Zipfian) · fit R² {:.2}",
        m.zipf_slope, m.zipf_r2
    );
    println!(
        "  syllables · {} attested / {} possible · saturation {:.0}%",
        m.attested_syllables,
        m.possible_syllables,
        m.syllable_saturation * 100.0,
    );
    println!(
        "  prosody   · {:.2} moras/word · {:.0}% heavy syllables",
        m.mean_moras,
        m.heavy_ratio * 100.0,
    );
}