feat: case-insensitive search for Markdown blocks and TXT text

crates/zx_document_core/src/search.rs

@@ -1,5 +1,9 @@
 use serde::{Deserialize, Serialize};
 
+use crate::blocks::DocumentBlock;
+
+const SNIPPET_RADIUS: usize = 40;
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct SearchResult {
     pub block_id: String,
@@ -8,3 +12,179 @@ pub struct SearchResult {
     pub match_start: usize,
     pub match_end: usize,
 }
+
+/// Search within a list of DocumentBlock (Markdown).
+pub fn search_blocks(blocks: &[DocumentBlock], query: &str) -> Vec<SearchResult> {
+    if query.is_empty() {
+        return Vec::new();
+    }
+    let query = query.to_lowercase();
+    let mut results = Vec::new();
+
+    for block in blocks {
+        let (block_id, text) = block_text(block);
+        if text.is_empty() {
+            continue;
+        }
+        let lower = text.to_lowercase();
+        let mut start = 0;
+        while let Some(pos) = lower[start..].find(&query) {
+            let abs_start = start + pos;
+            let abs_end = abs_start + query.len();
+
+            let snippet_start = abs_start.saturating_sub(SNIPPET_RADIUS);
+            let snippet_end = (abs_end + SNIPPET_RADIUS).min(text.len());
+            let snippet = if snippet_start > 0 {
+                format!("…{}", &text[snippet_start..snippet_end])
+            } else {
+                text[snippet_start..snippet_end].to_string()
+            };
+
+            results.push(SearchResult {
+                block_id: block_id.to_string(),
+                line_number: None,
+                snippet,
+                match_start: abs_start - snippet_start,
+                match_end: abs_end - snippet_start,
+            });
+
+            start = abs_end;
+            if start >= lower.len() {
+                break;
+            }
+        }
+    }
+
+    results
+}
+
+/// Search within a plain text string (TXT).
+pub fn search_text(content: &str, query: &str) -> Vec<SearchResult> {
+    if query.is_empty() {
+        return Vec::new();
+    }
+    let query = query.to_lowercase();
+    let lower = content.to_lowercase();
+    let mut results = Vec::new();
+    let mut start = 0;
+
+    while let Some(pos) = lower[start..].find(&query) {
+        let abs_start = start + pos;
+        let abs_end = abs_start + query.len();
+
+        // Determine line number
+        let line_number = content[..abs_start].lines().count() as u32;
+
+        let snippet_start = abs_start.saturating_sub(SNIPPET_RADIUS);
+        let snippet_end = (abs_end + SNIPPET_RADIUS).min(content.len());
+        let snippet = if snippet_start > 0 {
+            format!("…{}", &content[snippet_start..snippet_end])
+        } else {
+            content[snippet_start..snippet_end].to_string()
+        };
+
+        results.push(SearchResult {
+            block_id: format!("line-{line_number}"),
+            line_number: Some(line_number),
+            snippet,
+            match_start: abs_start - snippet_start,
+            match_end: abs_end - snippet_start,
+        });
+
+        start = abs_end;
+        if start >= lower.len() {
+            break;
+        }
+    }
+
+    results
+}
+
+fn block_text(block: &DocumentBlock) -> (&str, String) {
+    match block {
+        DocumentBlock::Heading { id, text, .. } => (id, text.clone()),
+        DocumentBlock::Paragraph { id, text, .. } => (id, text.clone()),
+        DocumentBlock::List { id, items, .. } => (id, items.join(" ")),
+        DocumentBlock::CodeBlock { id, code, .. } => (id, code.clone()),
+        DocumentBlock::Quote { id, text, .. } => (id, text.clone()),
+        DocumentBlock::Table { id, headers, rows } => {
+            let mut text = headers.join(" ");
+            for row in rows {
+                text.push(' ');
+                text.push_str(&row.join(" "));
+            }
+            (id, text)
+        }
+        DocumentBlock::Image { id, alt, .. } => (id, alt.clone().unwrap_or_default()),
+        DocumentBlock::HorizontalRule { .. } => ("", String::new()),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::markdown;
+
+    #[test]
+    fn test_search_blocks_basic() {
+        let md = "# Hello\n\nThis is a test document.\n\nMore content here.";
+        let blocks = markdown::parse_markdown(md).unwrap();
+        let results = search_blocks(&blocks, "test");
+        assert!(!results.is_empty());
+        assert!(results[0].snippet.to_lowercase().contains("test"));
+    }
+
+    #[test]
+    fn test_search_blocks_case_insensitive() {
+        let md = "Hello WORLD";
+        let blocks = markdown::parse_markdown(md).unwrap();
+        let lower = search_blocks(&blocks, "world");
+        let upper = search_blocks(&blocks, "WORLD");
+        assert_eq!(lower.len(), upper.len());
+    }
+
+    #[test]
+    fn test_search_blocks_no_match() {
+        let md = "# Title\n\nParagraph.";
+        let blocks = markdown::parse_markdown(md).unwrap();
+        let results = search_blocks(&blocks, "nonexistent");
+        assert!(results.is_empty());
+    }
+
+    #[test]
+    fn test_search_blocks_empty_query() {
+        let md = "Some text.";
+        let blocks = markdown::parse_markdown(md).unwrap();
+        let results = search_blocks(&blocks, "");
+        assert!(results.is_empty());
+    }
+
+    #[test]
+    fn test_search_text_basic() {
+        let content = "Line one\nLine two\nLine three";
+        let results = search_text(content, "two");
+        assert_eq!(results.len(), 1);
+        assert_eq!(results[0].line_number, Some(2));
+    }
+
+    #[test]
+    fn test_search_text_multiple_matches() {
+        let content = "hello world hello world hello world";
+        let results = search_text(content, "hello");
+        assert_eq!(results.len(), 3);
+    }
+
+    #[test]
+    fn test_search_text_no_match() {
+        let content = "just text";
+        let results = search_text(content, "xyz");
+        assert!(results.is_empty());
+    }
+
+    #[test]
+    fn test_search_text_empty_query() {
+        let content = "text";
+        let results = search_text(content, "");
+        assert!(results.is_empty());
+    }
+}