cargo-test-filter 0.1.0

use anyhow::{Context, Result};
use serde::{Deserialize, Serialize};
use std::fs;
use std::path::{Path, PathBuf};
use walkdir::WalkDir;

/// Represents an individual test function with its metadata
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct TestFunction {
    /// The name of the test function (e.g., "test_database_connection")
    pub name: String,
    /// The file containing this test
    pub file_path: PathBuf,
    /// The name of the test target (file stem for integration tests, "lib" for unit tests)
    pub target_name: String,
    /// The type of test (unit, integration, etc.)
    pub test_type: TestType,
    /// Tags associated with this specific test function
    pub tags: Vec<String>,
}

/// Legacy struct for file-level test targets (kept for compatibility)
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct TestTarget {
    pub name: String,
    pub path: PathBuf,
    pub test_type: TestType,
    pub tags: Vec<String>,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum TestType {
    Unit,
    Integration,
    Doc,
}

pub struct TestDiscovery {
    project_root: PathBuf,
}

impl TestDiscovery {
    pub fn new(project_root: PathBuf) -> Self {
        Self { project_root }
    }

    /// Discover all individual test functions in the project
    pub fn discover_test_functions(&self) -> Result<Vec<TestFunction>> {
        let mut functions = Vec::new();

        // Discover integration test functions
        functions.extend(self.discover_integration_test_functions()?);

        // Discover unit test functions in src/
        functions.extend(self.discover_unit_test_functions()?);

        Ok(functions)
    }

    /// Legacy method: Discover test targets (file-level)
    pub fn discover_tests(&self) -> Result<Vec<TestTarget>> {
        let mut tests = Vec::new();

        // Discover integration tests
        tests.extend(self.discover_integration_tests()?);

        // Discover unit tests in src/
        tests.extend(self.discover_unit_tests()?);

        Ok(tests)
    }

    /// Discover integration test functions in tests/ directory
    fn discover_integration_test_functions(&self) -> Result<Vec<TestFunction>> {
        let tests_dir = self.project_root.join("tests");
        if !tests_dir.exists() {
            return Ok(Vec::new());
        }

        let mut functions = Vec::new();

        for entry in WalkDir::new(&tests_dir)
            .min_depth(1)
            .max_depth(3)
            .into_iter()
            .filter_map(|e| e.ok())
        {
            let path = entry.path();
            if path.is_file() && path.extension().is_some_and(|e| e == "rs") {
                let target_name = path
                    .file_stem()
                    .and_then(|s| s.to_str())
                    .unwrap_or("unknown")
                    .to_string();

                let file_functions = self.parse_test_functions(path, &target_name, TestType::Integration)?;
                functions.extend(file_functions);
            }
        }

        Ok(functions)
    }

    /// Discover unit test functions in src/ directory
    fn discover_unit_test_functions(&self) -> Result<Vec<TestFunction>> {
        let src_dir = self.project_root.join("src");
        if !src_dir.exists() {
            return Ok(Vec::new());
        }

        let mut functions = Vec::new();

        for entry in WalkDir::new(&src_dir)
            .into_iter()
            .filter_map(|e| e.ok())
        {
            let path = entry.path();
            if path.is_file() && path.extension().is_some_and(|e| e == "rs") {
                let content = fs::read_to_string(path)
                    .with_context(|| format!("Failed to read {}", path.display()))?;

                if self.contains_tests(&content) {
                    let file_functions = self.parse_test_functions(path, "lib", TestType::Unit)?;
                    functions.extend(file_functions);
                }
            }
        }

        Ok(functions)
    }

    /// Parse a file to extract individual test functions with their tags
    fn parse_test_functions(&self, path: &Path, target_name: &str, test_type: TestType) -> Result<Vec<TestFunction>> {
        let content = fs::read_to_string(path)
            .with_context(|| format!("Failed to read {}", path.display()))?;

        let mut functions = Vec::new();
        let lines: Vec<&str> = content.lines().collect();
        let mut i = 0;

        while i < lines.len() {
            let line = lines[i].trim();

            // Look for #[test] or #[tokio::test] or similar test attributes
            if self.is_test_attribute(line) {
                // Collect tags from preceding lines
                let tags = self.collect_preceding_tags(&lines, i);

                // Find the function name from the next lines
                let func_name = self.find_function_name(&lines, i + 1);

                if let Some(name) = func_name {
                    functions.push(TestFunction {
                        name,
                        file_path: path.to_path_buf(),
                        target_name: target_name.to_string(),
                        test_type: test_type.clone(),
                        tags,
                    });
                }
            }

            i += 1;
        }

        Ok(functions)
    }

    /// Check if a line is a test attribute
    fn is_test_attribute(&self, line: &str) -> bool {
        let line = line.trim();
        // Match various test attributes
        line == "#[test]"
            || line.starts_with("#[test(")
            || line.starts_with("#[tokio::test")
            || line.starts_with("#[async_std::test")
            || line.starts_with("#[rstest")
            || line.starts_with("#[test_case")
    }

    /// Collect tags from lines preceding a test attribute
    fn collect_preceding_tags(&self, lines: &[&str], test_line_idx: usize) -> Vec<String> {
        let mut tags = Vec::new();

        // Look backwards from the test attribute for tag comments
        let mut j = test_line_idx;
        while j > 0 {
            j -= 1;
            let line = lines[j].trim();

            // Stop if we hit an empty line or something that's not a comment/attribute
            if line.is_empty() {
                break;
            }

            // Parse tag from comment or attribute
            if let Some(tag) = self.parse_tag_line(line) {
                tags.push(tag);
            } else if !line.starts_with("//") && !line.starts_with("#[") {
                // Hit non-comment, non-attribute line - stop looking
                break;
            }
        }

        tags
    }

    /// Parse a tag from a line (supports multiple formats)
    fn parse_tag_line(&self, line: &str) -> Option<String> {
        let line = line.trim();

        // Support comment-based tags: // @tag: tagname or //@tag: tagname
        if line.starts_with("// @tag:") || line.starts_with("//@tag:") {
            let parts: Vec<&str> = line.splitn(2, ':').collect();
            if parts.len() >= 2 {
                return Some(parts[1].trim().to_string());
            }
        }

        // Support attribute-based tags: #[test_tag("tagname")]
        if line.starts_with("#[test_tag(") && line.ends_with(")]") {
            let start = line.find('"')?;
            let end = line.rfind('"')?;
            if start < end {
                return Some(line[start + 1..end].to_string());
            }
        }

        None
    }

    /// Find the function name after a test attribute
    fn find_function_name(&self, lines: &[&str], start_idx: usize) -> Option<String> {
        for line in lines.iter().skip(start_idx).take(5) {
            let line = line.trim();

            // Skip additional attributes
            if line.starts_with("#[") {
                continue;
            }

            // Look for function definition
            if line.starts_with("fn ") || line.starts_with("pub fn ") || line.starts_with("async fn ") || line.starts_with("pub async fn ") {
                // Extract function name
                let without_prefix = line
                    .trim_start_matches("pub ")
                    .trim_start_matches("async ")
                    .trim_start_matches("fn ");

                // Get the function name (everything before '(' or '<')
                let name_end = without_prefix.find(['(', '<', ' ']).unwrap_or(without_prefix.len());
                let name = without_prefix[..name_end].trim().to_string();

                if !name.is_empty() {
                    return Some(name);
                }
            }
        }

        None
    }

    /// Legacy: Discover integration tests in tests/ directory (file-level)
    fn discover_integration_tests(&self) -> Result<Vec<TestTarget>> {
        let tests_dir = self.project_root.join("tests");
        if !tests_dir.exists() {
            return Ok(Vec::new());
        }

        let mut targets = Vec::new();

        for entry in WalkDir::new(&tests_dir)
            .min_depth(1)
            .max_depth(3)
            .into_iter()
            .filter_map(|e| e.ok())
        {
            let path = entry.path();
            if path.is_file() && path.extension().is_some_and(|e| e == "rs") {
                let tags = self.extract_file_tags(path)?;
                let name = path
                    .file_stem()
                    .and_then(|s| s.to_str())
                    .unwrap_or("unknown")
                    .to_string();

                targets.push(TestTarget {
                    name,
                    path: path.to_path_buf(),
                    test_type: TestType::Integration,
                    tags,
                });
            }
        }

        Ok(targets)
    }

    /// Legacy: Discover unit tests in src/ directory (file-level)
    fn discover_unit_tests(&self) -> Result<Vec<TestTarget>> {
        let src_dir = self.project_root.join("src");
        if !src_dir.exists() {
            return Ok(Vec::new());
        }

        let mut targets = Vec::new();

        for entry in WalkDir::new(&src_dir)
            .into_iter()
            .filter_map(|e| e.ok())
        {
            let path = entry.path();
            if path.is_file() && path.extension().is_some_and(|e| e == "rs") {
                let content = fs::read_to_string(path)
                    .with_context(|| format!("Failed to read {}", path.display()))?;

                if self.contains_tests(&content) {
                    let tags = self.extract_file_tags(path)?;
                    let name = path
                        .file_stem()
                        .and_then(|s| s.to_str())
                        .unwrap_or("unknown")
                        .to_string();

                    targets.push(TestTarget {
                        name,
                        path: path.to_path_buf(),
                        test_type: TestType::Unit,
                        tags,
                    });
                }
            }
        }

        Ok(targets)
    }

    /// Check if a file contains test functions
    fn contains_tests(&self, content: &str) -> bool {
        content.contains("#[test]") || content.contains("#[cfg(test)]")
    }

    /// Extract all tags from a file (for legacy file-level support)
    fn extract_file_tags(&self, path: &Path) -> Result<Vec<String>> {
        let content = fs::read_to_string(path)
            .with_context(|| format!("Failed to read {}", path.display()))?;

        let mut tags = Vec::new();

        for line in content.lines() {
            if let Some(tag) = self.parse_tag_line(line) {
                if !tags.contains(&tag) {
                    tags.push(tag);
                }
            }
        }

        Ok(tags)
    }

    /// Get the project root by looking for Cargo.toml
    pub fn find_project_root() -> Result<PathBuf> {
        let current_dir = std::env::current_dir()
            .context("Failed to get current directory")?;

        let mut dir = current_dir.as_path();
        loop {
            if dir.join("Cargo.toml").exists() {
                return Ok(dir.to_path_buf());
            }
            dir = dir.parent().context("Failed to find Cargo.toml in parent directories")?;
        }
    }
}

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

    #[test]
    fn test_is_test_attribute() {
        let discovery = TestDiscovery::new(PathBuf::from("."));

        assert!(discovery.is_test_attribute("#[test]"));
        assert!(discovery.is_test_attribute("#[tokio::test]"));
        assert!(discovery.is_test_attribute("#[async_std::test]"));
        assert!(!discovery.is_test_attribute("fn test_something()"));
        assert!(!discovery.is_test_attribute("// #[test]"));
    }

    #[test]
    fn test_parse_tag_line() {
        let discovery = TestDiscovery::new(PathBuf::from("."));

        assert_eq!(discovery.parse_tag_line("// @tag: fast"), Some("fast".to_string()));
        assert_eq!(discovery.parse_tag_line("//@tag: slow"), Some("slow".to_string()));
        assert_eq!(discovery.parse_tag_line("#[test_tag(\"database\")]"), Some("database".to_string()));
        assert_eq!(discovery.parse_tag_line("fn test()"), None);
    }

    #[test]
    fn test_find_function_name() {
        let discovery = TestDiscovery::new(PathBuf::from("."));

        let lines = vec![
            "fn test_something() {",
            "    assert!(true);",
            "}",
        ];
        assert_eq!(discovery.find_function_name(&lines, 0), Some("test_something".to_string()));

        let lines2 = vec![
            "pub fn test_public() {",
        ];
        assert_eq!(discovery.find_function_name(&lines2, 0), Some("test_public".to_string()));

        let lines3 = vec![
            "async fn test_async() {",
        ];
        assert_eq!(discovery.find_function_name(&lines3, 0), Some("test_async".to_string()));
    }
}