use anyhow::{Context, Result};
use regex::Regex;
use std::path::{Path, PathBuf};
use std::process::Command;

const TEST_FILE_NAME: &str = "TEST.sh";

/// Result of running all tests for a single skill.
#[derive(Debug, Clone)]
pub struct SkillTestResult {
    pub skill_name: String,
    pub tests_run: usize,
    pub tests_passed: usize,
    pub failures: Vec<TestFailure>,
}

/// Details about a single failed test case.
#[derive(Debug, Clone)]
pub struct TestFailure {
    pub command: String,
    pub expected_exit: i32,
    pub actual_exit: i32,
    pub expected_pattern: String,
    pub actual_output: String,
}

/// A parsed test case from a TEST.sh line.
#[derive(Debug, Clone)]
struct TestCase {
    command: String,
    expected_exit: i32,
    expected_pattern: String,
}

/// Parse a single TEST.sh line into a `TestCase`.
///
/// Expected format: `command | expected_exit_code | expected_output_pattern`
fn parse_test_line(line: &str) -> Option<TestCase> {
    let trimmed = line.trim();
    if trimmed.is_empty() || trimmed.starts_with('#') {
        return None;
    }

    // Split on ` | ` (pipe surrounded by spaces) to avoid splitting on shell
    // pipes inside the command itself. Fall back to bare `|` splitting only if
    // the line contains exactly two ` | ` delimiters.
    let parts: Vec<&str> = trimmed.split(" | ").collect();
    if parts.len() < 3 {
        // Try splitting on `|` as fallback
        let parts: Vec<&str> = trimmed.splitn(3, '|').collect();
        if parts.len() < 3 {
            return None;
        }
        let command = parts[0].trim().to_string();
        let expected_exit = parts[1].trim().parse::<i32>().ok()?;
        let expected_pattern = parts[2].trim().to_string();
        return Some(TestCase {
            command,
            expected_exit,
            expected_pattern,
        });
    }

    let command = parts[0].trim().to_string();
    let expected_exit = parts[1].trim().parse::<i32>().ok()?;
    // Rejoin remaining parts in case the pattern itself contains ` | `
    let expected_pattern = parts[2..].join(" | ").trim().to_string();

    Some(TestCase {
        command,
        expected_exit,
        expected_pattern,
    })
}

/// Check whether `output` matches `pattern`.
///
/// If the pattern looks like a regex (contains regex metacharacters beyond a
/// simple `/` path), we attempt a regex match. Otherwise we fall back to a
/// simple substring check.
fn pattern_matches(output: &str, pattern: &str) -> bool {
    if pattern.is_empty() {
        return true;
    }
    // Try regex first
    if let Ok(re) = Regex::new(pattern) {
        if re.is_match(output) {
            return true;
        }
    }
    // Fallback: substring match
    output.contains(pattern)
}

/// Run a single test case and return a possible failure.
fn run_test_case(case: &TestCase, skill_dir: &Path, verbose: bool) -> Option<TestFailure> {
    if verbose {
        println!("    running: {}", case.command);
    }

    let result = Command::new("sh")
        .arg("-c")
        .arg(&case.command)
        .current_dir(skill_dir)
        .output();

    let output = match result {
        Ok(o) => o,
        Err(err) => {
            return Some(TestFailure {
                command: case.command.clone(),
                expected_exit: case.expected_exit,
                actual_exit: -1,
                expected_pattern: case.expected_pattern.clone(),
                actual_output: format!("failed to execute command: {err}"),
            });
        }
    };

    let actual_exit = output.status.code().unwrap_or(-1);
    let stdout = String::from_utf8_lossy(&output.stdout);
    let stderr = String::from_utf8_lossy(&output.stderr);
    let combined = format!("{stdout}{stderr}");

    if verbose {
        if !stdout.is_empty() {
            println!("    stdout: {}", stdout.trim());
        }
        if !stderr.is_empty() {
            println!("    stderr: {}", stderr.trim());
        }
        println!("    exit: {actual_exit}");
    }

    let exit_ok = actual_exit == case.expected_exit;
    let pattern_ok = pattern_matches(&combined, &case.expected_pattern);

    if exit_ok && pattern_ok {
        None
    } else {
        Some(TestFailure {
            command: case.command.clone(),
            expected_exit: case.expected_exit,
            actual_exit,
            expected_pattern: case.expected_pattern.clone(),
            actual_output: combined.to_string(),
        })
    }
}

/// Test a single skill by parsing and running its TEST.sh.
pub fn test_skill(skill_dir: &Path, skill_name: &str, verbose: bool) -> Result<SkillTestResult> {
    let test_file = skill_dir.join(TEST_FILE_NAME);
    if !test_file.exists() {
        return Ok(SkillTestResult {
            skill_name: skill_name.to_string(),
            tests_run: 0,
            tests_passed: 0,
            failures: Vec::new(),
        });
    }

    let content = std::fs::read_to_string(&test_file)
        .with_context(|| format!("failed to read {}", test_file.display()))?;

    let cases: Vec<TestCase> = content.lines().filter_map(parse_test_line).collect();

    let mut result = SkillTestResult {
        skill_name: skill_name.to_string(),
        tests_run: cases.len(),
        tests_passed: 0,
        failures: Vec::new(),
    };

    for case in &cases {
        match run_test_case(case, skill_dir, verbose) {
            None => result.tests_passed += 1,
            Some(failure) => result.failures.push(failure),
        }
    }

    Ok(result)
}

/// Test all skills that have a TEST.sh file within the given skill directories.
pub fn test_all_skills(skills_dirs: &[PathBuf], verbose: bool) -> Result<Vec<SkillTestResult>> {
    let mut results = Vec::new();

    for dir in skills_dirs {
        if !dir.exists() || !dir.is_dir() {
            continue;
        }

        let entries = std::fs::read_dir(dir)
            .with_context(|| format!("failed to read directory {}", dir.display()))?;

        for entry in entries.flatten() {
            let path = entry.path();
            if !path.is_dir() {
                continue;
            }
            let test_file = path.join(TEST_FILE_NAME);
            if !test_file.exists() {
                continue;
            }
            let skill_name = path
                .file_name()
                .map(|n| n.to_string_lossy().to_string())
                .unwrap_or_default();

            if verbose {
                println!("  Testing skill: {} ({})", skill_name, path.display());
            }

            let r = test_skill(&path, &skill_name, verbose)?;
            results.push(r);
        }
    }

    Ok(results)
}

/// Pretty-print test results using the `console` crate.
pub fn print_results(results: &[SkillTestResult]) {
    if results.is_empty() {
        println!("No skills with {} found.", TEST_FILE_NAME);
        return;
    }

    println!();
    for r in results {
        if r.tests_run == 0 {
            println!(
                "  {} {} — no test cases",
                console::style("-").dim(),
                r.skill_name,
            );
            continue;
        }

        if r.failures.is_empty() {
            println!(
                "  {} {} — {}/{} passed",
                console::style("✓").green().bold(),
                console::style(&r.skill_name).white().bold(),
                r.tests_passed,
                r.tests_run,
            );
        } else {
            println!(
                "  {} {} — {}/{} passed",
                console::style("✗").red().bold(),
                console::style(&r.skill_name).white().bold(),
                r.tests_passed,
                r.tests_run,
            );
            for f in &r.failures {
                println!("    command:  {}", console::style(&f.command).dim(),);
                println!(
                    "    expected: exit={}, pattern={}",
                    f.expected_exit, f.expected_pattern,
                );
                println!(
                    "    actual:   exit={}, output={}",
                    f.actual_exit,
                    truncate_output(&f.actual_output, 200),
                );
                println!();
            }
        }
    }

    let total_run: usize = results.iter().map(|r| r.tests_run).sum();
    let total_passed: usize = results.iter().map(|r| r.tests_passed).sum();
    let total_failed = total_run - total_passed;

    println!();
    if total_failed == 0 {
        println!(
            "  {} All {total_run} test(s) passed across {} skill(s).",
            console::style("✓").green().bold(),
            results.len(),
        );
    } else {
        println!(
            "  {} {total_failed} of {total_run} test(s) failed across {} skill(s).",
            console::style("✗").red().bold(),
            results.len(),
        );
    }
    println!();
}

fn truncate_output(s: &str, max: usize) -> String {
    let trimmed = s.trim();
    if trimmed.len() <= max {
        trimmed.replace('\n', " ")
    } else {
        format!("{}...", &trimmed[..max].replace('\n', " "))
    }
}

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

    #[test]
    fn parse_comment_and_empty_lines() {
        assert!(parse_test_line("").is_none());
        assert!(parse_test_line("   ").is_none());
        assert!(parse_test_line("# this is a comment").is_none());
        assert!(parse_test_line("  # indented comment").is_none());
    }

    #[test]
    fn parse_valid_test_line() {
        let case = parse_test_line("echo hello | 0 | hello").unwrap();
        assert_eq!(case.command, "echo hello");
        assert_eq!(case.expected_exit, 0);
        assert_eq!(case.expected_pattern, "hello");
    }

    #[test]
    fn parse_line_with_spaces_in_pattern() {
        let case = parse_test_line("echo 'hello world' | 0 | hello world").unwrap();
        assert_eq!(case.command, "echo 'hello world'");
        assert_eq!(case.expected_exit, 0);
        assert_eq!(case.expected_pattern, "hello world");
    }

    #[test]
    fn parse_invalid_line_missing_parts() {
        assert!(parse_test_line("just a command").is_none());
        assert!(parse_test_line("cmd | notanumber | pattern").is_none());
    }

    #[test]
    fn pattern_matches_empty() {
        assert!(pattern_matches("anything", ""));
    }

    #[test]
    fn pattern_matches_substring() {
        assert!(pattern_matches("hello world", "hello"));
        assert!(pattern_matches("hello world", "world"));
        assert!(!pattern_matches("hello world", "missing"));
    }

    #[test]
    fn pattern_matches_regex() {
        assert!(pattern_matches("hello world 42", r"world \d+"));
        assert!(pattern_matches("/usr/bin/bash", r"/"));
        assert!(!pattern_matches("hello", r"^\d+$"));
    }

    #[test]
    fn test_skill_with_echo() {
        let dir = tempfile::tempdir().unwrap();
        let skill_dir = dir.path().join("echo-skill");
        fs::create_dir_all(&skill_dir).unwrap();
        fs::write(
            skill_dir.join("TEST.sh"),
            "# Echo test\necho hello | 0 | hello\n",
        )
        .unwrap();

        let result = test_skill(&skill_dir, "echo-skill", false).unwrap();
        assert_eq!(result.tests_run, 1);
        assert_eq!(result.tests_passed, 1);
        assert!(result.failures.is_empty());
    }

    #[test]
    fn test_skill_without_test_file() {
        let dir = tempfile::tempdir().unwrap();
        let skill_dir = dir.path().join("no-tests");
        fs::create_dir_all(&skill_dir).unwrap();

        let result = test_skill(&skill_dir, "no-tests", false).unwrap();
        assert_eq!(result.tests_run, 0);
        assert_eq!(result.tests_passed, 0);
        assert!(result.failures.is_empty());
    }

    #[test]
    fn test_skill_with_failing_test() {
        let dir = tempfile::tempdir().unwrap();
        let skill_dir = dir.path().join("fail-skill");
        fs::create_dir_all(&skill_dir).unwrap();
        fs::write(skill_dir.join("TEST.sh"), "echo hello | 1 | goodbye\n").unwrap();

        let result = test_skill(&skill_dir, "fail-skill", false).unwrap();
        assert_eq!(result.tests_run, 1);
        assert_eq!(result.tests_passed, 0);
        assert_eq!(result.failures.len(), 1);
        assert_eq!(result.failures[0].expected_exit, 1);
        assert_eq!(result.failures[0].actual_exit, 0);
    }

    #[test]
    fn test_skill_exit_code_mismatch() {
        let dir = tempfile::tempdir().unwrap();
        let skill_dir = dir.path().join("exit-mismatch");
        fs::create_dir_all(&skill_dir).unwrap();
        fs::write(skill_dir.join("TEST.sh"), "false | 0 | \n").unwrap();

        let result = test_skill(&skill_dir, "exit-mismatch", false).unwrap();
        assert_eq!(result.tests_run, 1);
        assert_eq!(result.tests_passed, 0);
        assert_eq!(result.failures[0].actual_exit, 1);
    }

    #[test]
    fn test_result_aggregation() {
        let results = [
            SkillTestResult {
                skill_name: "a".to_string(),
                tests_run: 3,
                tests_passed: 3,
                failures: Vec::new(),
            },
            SkillTestResult {
                skill_name: "b".to_string(),
                tests_run: 2,
                tests_passed: 1,
                failures: vec![TestFailure {
                    command: "false".to_string(),
                    expected_exit: 0,
                    actual_exit: 1,
                    expected_pattern: String::new(),
                    actual_output: String::new(),
                }],
            },
        ];

        let total_run: usize = results.iter().map(|r| r.tests_run).sum();
        let total_passed: usize = results.iter().map(|r| r.tests_passed).sum();
        assert_eq!(total_run, 5);
        assert_eq!(total_passed, 4);
    }

    #[test]
    fn test_all_skills_finds_skills_with_tests() {
        let dir = tempfile::tempdir().unwrap();
        let skills_dir = dir.path().join("skills");

        // Skill with TEST.sh
        let skill_a = skills_dir.join("skill-a");
        fs::create_dir_all(&skill_a).unwrap();
        fs::write(skill_a.join("TEST.sh"), "echo ok | 0 | ok\n").unwrap();

        // Skill without TEST.sh — should be skipped
        let skill_b = skills_dir.join("skill-b");
        fs::create_dir_all(&skill_b).unwrap();

        let results = test_all_skills(std::slice::from_ref(&skills_dir), false).unwrap();
        assert_eq!(results.len(), 1);
        assert_eq!(results[0].skill_name, "skill-a");
        assert_eq!(results[0].tests_passed, 1);
    }

    #[test]
    fn test_truncate_output() {
        assert_eq!(truncate_output("short", 100), "short");
        let long = "a".repeat(300);
        let truncated = truncate_output(&long, 200);
        assert!(truncated.ends_with("..."));
        assert!(truncated.len() <= 204); // 200 + "..."
    }
}
