triplets 0.15.0-alpha

//! Text normalization helpers shared by source implementations.

use chrono::{DateTime, Utc};
use line_ending::LineEnding;
use std::fs;
use std::path::Path;

use crate::data::{RecordSection, SectionRole};
use crate::types::Sentence;

/// Returns the newline string for the current platform (`"\n"` on Unix, `"\r\n"` on Windows).
pub fn platform_newline() -> &'static str {
    LineEnding::from_current_platform().as_str()
}

/// Collapse repeated whitespace in-place while preserving single spaces.
/// Collapse runs of whitespace into single spaces and trim.
pub fn normalize_inline_whitespace<T: AsRef<str>>(text: T) -> String {
    let mut normalized = String::new();
    let mut seen_space = false;
    for ch in text.as_ref().chars() {
        if ch.is_whitespace() {
            if !seen_space {
                normalized.push(' ');
                seen_space = true;
            }
        } else {
            normalized.push(ch);
            seen_space = false;
        }
    }
    normalized.trim().to_string()
}

/// Split a block of text into sentences, falling back to the whole string when needed.
/// Heuristic sentence splitter with tokenizer-friendly rules.
pub fn sentences(text: &str) -> Vec<Sentence> {
    let mut results = Vec::new();
    let normalized = LineEnding::normalize(text);
    let paragraph_sep = LineEnding::LF.as_str().repeat(2);
    for block in normalized.split(&paragraph_sep) {
        if block.trim().is_empty() {
            continue;
        }
        let normalized = normalize_inline_whitespace(block);
        if normalized.is_empty() {
            continue;
        }
        push_block_sentences(&normalized, &mut results);
    }

    results
}

/// Convenience helper to construct a `RecordSection` with normalized text metadata.
/// Convenience helper to build a `RecordSection` with precomputed sentences.
pub fn make_section(role: SectionRole, heading: Option<&str>, text: &str) -> RecordSection {
    RecordSection {
        role,
        heading: heading.map(|h| h.to_string()),
        text: text.to_string(),
        sentences: sentences(text),
    }
}

fn push_block_sentences(block: &str, results: &mut Vec<Sentence>) {
    let chars: Vec<char> = block.chars().collect();
    let mut buffer = String::new();

    for (idx, ch) in chars.iter().enumerate() {
        buffer.push(*ch);
        if is_sentence_boundary(&chars, idx) {
            let trimmed = buffer.trim();
            if !trimmed.is_empty() {
                results.push(trimmed.to_string());
            }
            buffer.clear();
        }
    }

    let trailing = buffer.trim();
    if !trailing.is_empty() {
        results.push(trailing.to_string());
    }
}

fn is_sentence_boundary(chars: &[char], idx: usize) -> bool {
    match chars[idx] {
        '.' => is_dot_boundary(chars, idx),
        '!' | '?' => true,
        _ => false,
    }
}

fn is_dot_boundary(chars: &[char], idx: usize) -> bool {
    if is_decimal_middle(chars, idx) || is_ticker_middle(chars, idx) {
        return false;
    }
    if idx + 1 < chars.len() && chars[idx + 1] == '.' {
        return false;
    }
    true
}

fn is_decimal_middle(chars: &[char], idx: usize) -> bool {
    idx > 0
        && idx + 1 < chars.len()
        && chars[idx - 1].is_ascii_digit()
        && chars[idx + 1].is_ascii_digit()
}

fn is_ticker_middle(chars: &[char], idx: usize) -> bool {
    idx > 0
        && idx + 1 < chars.len()
        && is_ticker_char(chars[idx - 1])
        && is_ticker_char(chars[idx + 1])
}

fn is_ticker_char(ch: char) -> bool {
    ch.is_ascii_uppercase() || ch.is_ascii_digit()
}

// ---------------------------------------------------------------------------
// Filesystem helpers
// ---------------------------------------------------------------------------

/// True if the path has a `.txt` extension (case-insensitive).
pub fn is_text_file(path: &Path) -> bool {
    path.extension()
        .and_then(|ext| ext.to_str())
        .map(|ext| ext.eq_ignore_ascii_case("txt"))
        .unwrap_or(false)
}

/// Best-effort file modified time.
pub fn file_mtime(path: &Path) -> Option<DateTime<Utc>> {
    let metadata = fs::metadata(path).ok()?;
    let modified = metadata.modified().ok()?;
    Some(system_time_to_utc(modified))
}

/// Best-effort (created_at, updated_at) pair for a file.
pub fn file_times(path: &Path) -> (DateTime<Utc>, DateTime<Utc>) {
    let metadata = fs::metadata(path).ok();
    let updated_at = metadata
        .as_ref()
        .and_then(|meta| meta.modified().ok())
        .map(system_time_to_utc)
        .unwrap_or_else(Utc::now);
    let created_at = metadata
        .and_then(|meta| meta.created().ok())
        .map(system_time_to_utc)
        .unwrap_or(updated_at);
    (created_at, updated_at)
}

fn system_time_to_utc(time: std::time::SystemTime) -> DateTime<Utc> {
    DateTime::<Utc>::from(time)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn normalize_inline_whitespace_collapses_runs() {
        let nl = platform_newline();
        let input = format!("Alpha{nl}{nl}  Beta\tGamma");
        assert_eq!(normalize_inline_whitespace(&input), "Alpha Beta Gamma");
    }

    #[test]
    fn sentences_falls_back_to_full_text_when_needed() {
        let text = format!("   {}", platform_newline());
        let result = sentences(&text);
        assert!(result.is_empty());

        let text2 = "Single block without punctuation";
        let result2 = sentences(text2);
        assert_eq!(
            result2,
            vec![String::from("Single block without punctuation")]
        );
    }

    #[test]
    fn make_section_populates_sentences() {
        let section = make_section(SectionRole::Context, Some("Summary"), "Line one. Line two!");
        assert_eq!(section.heading.as_deref(), Some("Summary"));
        assert_eq!(section.sentences.len(), 2);
        assert_eq!(section.role, SectionRole::Context);
    }

    #[test]
    fn sentences_keep_decimal_values_together() {
        let text = "Price closed at 3.14. Outlook improved.";
        let result = sentences(text);
        assert_eq!(result, vec!["Price closed at 3.14.", "Outlook improved."]);
    }

    #[test]
    fn sentences_keep_dot_tickers_together() {
        let text = "BRK.B rallied while RDS.A lagged.";
        let result = sentences(text);
        assert_eq!(result, vec!["BRK.B rallied while RDS.A lagged."]);
    }

    #[test]
    fn file_time_helpers_handle_existing_and_missing_paths() {
        use tempfile::tempdir;
        let temp = tempdir().unwrap();
        let existing = temp.path().join("exists.txt");
        std::fs::write(&existing, "hello").unwrap();

        assert!(file_mtime(&existing).is_some());
        let (created_at, updated_at) = file_times(&existing);
        assert!(updated_at >= created_at);

        let missing = temp.path().join("missing.txt");
        assert!(file_mtime(&missing).is_none());
        let (missing_created, missing_updated) = file_times(&missing);
        assert!(missing_updated >= missing_created);
    }

    #[test]
    fn sentences_treat_blank_line_as_boundary() {
        let nl = platform_newline();
        let text = format!("First line without punctuation{nl}{nl}Second line with more context.");
        let result = sentences(&text);
        assert_eq!(
            result,
            vec![
                "First line without punctuation".to_string(),
                "Second line with more context.".to_string()
            ]
        );
    }

    #[test]
    fn sentences_keep_ellipsis_together() {
        let text = "Wait... really? Yes.";
        let result = sentences(text);
        assert_eq!(result, vec!["Wait...", "really?", "Yes."]);
    }

    #[test]
    fn is_text_file_matches_txt_case_insensitively() {
        use std::path::PathBuf;
        assert!(is_text_file(&PathBuf::from("hello.txt")));
        assert!(is_text_file(&PathBuf::from("hello.TXT")));
        assert!(is_text_file(&PathBuf::from("hello.Txt")));
        assert!(!is_text_file(&PathBuf::from("hello.md")));
        assert!(!is_text_file(&PathBuf::from("hello")));
    }
}