use acp_thread::PermissionPattern;
use shell_command_parser::{extract_commands, extract_terminal_command_prefix};
use std::path::{Path, PathBuf};
use url::Url;

/// Escapes a string for use in a regex pattern, but leaves dashes unescaped.
///
/// `regex::escape()` escapes dashes, but they are only special inside `[]`
/// character classes. Leaving them unescaped produces cleaner patterns
/// (e.g. `^git-lfs\s+pull` instead of `^git\-lfs\s+pull`).
fn escape_for_pattern(text: &str) -> String {
    regex::escape(text).replace("\\-", "-")
}

/// Normalize path separators to forward slashes for consistent cross-platform patterns.
fn normalize_separators(path_str: &str) -> String {
    path_str.replace('\\', "/")
}

/// Returns true if the token looks like a command name or subcommand — i.e. it
/// contains only alphanumeric characters, hyphens, and underscores, and does not
/// start with a hyphen (which would make it a flag).
fn is_plain_command_token(token: &str) -> bool {
    !token.starts_with('-')
        && token
            .chars()
            .all(|c| c.is_alphanumeric() || c == '-' || c == '_')
}

struct CommandPrefix {
    normalized_tokens: Vec<String>,
    display: String,
}

/// Extracts the command name and optional subcommand from a shell command using
/// the shell parser.
///
/// This parses the command properly to extract the command name and optional
/// subcommand (e.g. "cargo" and "test" from "cargo test -p search"), handling shell
/// syntax correctly. Returns `None` if parsing fails or if the command name
/// contains path separators (for security reasons).
fn extract_command_prefix(command: &str) -> Option<CommandPrefix> {
    let prefix = extract_terminal_command_prefix(command)?;

    if !is_plain_command_token(&prefix.command) {
        return None;
    }

    Some(CommandPrefix {
        normalized_tokens: prefix.tokens,
        display: prefix.display,
    })
}

/// Extracts a regex pattern and display name from a terminal command.
///
/// Returns `None` for commands starting with `./`, `/`, or other path-like prefixes.
/// This is a deliberate security decision: we only allow pattern-based "always allow"
/// rules for well-known command names (like `cargo`, `npm`, `git`), not for arbitrary
/// scripts or absolute paths which could be manipulated by an attacker.
pub fn extract_terminal_permission_pattern(command: &str) -> Option<PermissionPattern> {
    let pattern = extract_terminal_pattern(command)?;
    let display_name = extract_terminal_pattern_display(command)?;
    Some(PermissionPattern {
        pattern,
        display_name,
    })
}

pub fn extract_terminal_pattern(command: &str) -> Option<String> {
    let prefix = extract_command_prefix(command)?;
    let tokens = prefix.normalized_tokens;

    match tokens.as_slice() {
        [] => None,
        [single] => Some(format!("^{}\\b", escape_for_pattern(single))),
        [rest @ .., last] => Some(format!(
            "^{}\\s+{}(\\s|$)",
            rest.iter()
                .map(|token| escape_for_pattern(token))
                .collect::<Vec<_>>()
                .join("\\s+"),
            escape_for_pattern(last)
        )),
    }
}

pub fn extract_terminal_pattern_display(command: &str) -> Option<String> {
    let prefix = extract_command_prefix(command)?;
    Some(prefix.display)
}

/// Extracts patterns for ALL commands in a pipeline, not just the first one.
///
/// For a command like `"cargo test 2>&1 | tail"`, this returns patterns for
/// both `cargo` and `tail`. Path-based commands (e.g. `./script.sh`) are
/// filtered out, and duplicate command names are deduplicated while preserving
/// order.
pub fn extract_all_terminal_patterns(command: &str) -> Vec<PermissionPattern> {
    let commands = match extract_commands(command) {
        Some(commands) => commands,
        None => return Vec::new(),
    };

    let mut results = Vec::new();

    for cmd in &commands {
        let Some(permission_pattern) = extract_terminal_permission_pattern(cmd) else {
            continue;
        };

        if results.contains(&permission_pattern) {
            continue;
        }

        results.push(permission_pattern);
    }

    results
}

pub fn extract_path_pattern(path: &str) -> Option<String> {
    let parent = Path::new(path).parent()?;
    let parent_str = normalize_separators(parent.to_str()?);
    if parent_str.is_empty() || parent_str == "/" {
        return None;
    }
    Some(format!("^{}/", escape_for_pattern(&parent_str)))
}

pub fn extract_path_pattern_display(path: &str) -> Option<String> {
    let parent = Path::new(path).parent()?;
    let parent_str = normalize_separators(parent.to_str()?);
    if parent_str.is_empty() || parent_str == "/" {
        return None;
    }
    Some(format!("{}/", parent_str))
}

fn common_parent_dir(path_a: &str, path_b: &str) -> Option<PathBuf> {
    let parent_a = Path::new(path_a).parent()?;
    let parent_b = Path::new(path_b).parent()?;

    let components_a: Vec<_> = parent_a.components().collect();
    let components_b: Vec<_> = parent_b.components().collect();

    let common_count = components_a
        .iter()
        .zip(components_b.iter())
        .take_while(|(a, b)| a == b)
        .count();

    if common_count == 0 {
        return None;
    }

    let common: PathBuf = components_a[..common_count].iter().collect();
    Some(common)
}

pub fn extract_copy_move_pattern(input: &str) -> Option<String> {
    let (source, dest) = input.split_once('\n')?;
    let common = common_parent_dir(source, dest)?;
    let common_str = normalize_separators(common.to_str()?);
    if common_str.is_empty() || common_str == "/" {
        return None;
    }
    Some(format!("^{}/", escape_for_pattern(&common_str)))
}

pub fn extract_copy_move_pattern_display(input: &str) -> Option<String> {
    let (source, dest) = input.split_once('\n')?;
    let common = common_parent_dir(source, dest)?;
    let common_str = normalize_separators(common.to_str()?);
    if common_str.is_empty() || common_str == "/" {
        return None;
    }
    Some(format!("{}/", common_str))
}

pub fn extract_url_pattern(url: &str) -> Option<String> {
    let parsed = Url::parse(url).ok()?;
    let domain = parsed.host_str()?;
    Some(format!("^https?://{}", escape_for_pattern(domain)))
}

pub fn extract_url_pattern_display(url: &str) -> Option<String> {
    let parsed = Url::parse(url).ok()?;
    let domain = parsed.host_str()?;
    Some(domain.to_string())
}

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

    #[test]
    fn test_extract_terminal_pattern() {
        assert_eq!(
            extract_terminal_pattern("cargo build --release"),
            Some("^cargo\\s+build(\\s|$)".to_string())
        );
        assert_eq!(
            extract_terminal_pattern("cargo test -p search"),
            Some("^cargo\\s+test(\\s|$)".to_string())
        );
        assert_eq!(
            extract_terminal_pattern("npm install"),
            Some("^npm\\s+install(\\s|$)".to_string())
        );
        assert_eq!(
            extract_terminal_pattern("git-lfs pull"),
            Some("^git-lfs\\s+pull(\\s|$)".to_string())
        );
        assert_eq!(
            extract_terminal_pattern("my_script arg"),
            Some("^my_script\\s+arg(\\s|$)".to_string())
        );

        // Flags as second token: only the command name is used
        assert_eq!(
            extract_terminal_pattern("ls -la"),
            Some("^ls\\b".to_string())
        );
        assert_eq!(
            extract_terminal_pattern("rm --force foo"),
            Some("^rm\\b".to_string())
        );

        // Single-word commands
        assert_eq!(extract_terminal_pattern("ls"), Some("^ls\\b".to_string()));

        // Subcommand pattern does not match a hyphenated extension of the subcommand
        // (e.g. approving "cargo build" should not approve "cargo build-foo")
        assert_eq!(
            extract_terminal_pattern("cargo build"),
            Some("^cargo\\s+build(\\s|$)".to_string())
        );
        let pattern = regex::Regex::new(&extract_terminal_pattern("cargo build").unwrap()).unwrap();
        assert!(pattern.is_match("cargo build --release"));
        assert!(pattern.is_match("cargo build"));
        assert!(!pattern.is_match("cargo build-foo"));
        assert!(!pattern.is_match("cargo builder"));

        // Env-var prefixes are included in generated patterns
        assert_eq!(
            extract_terminal_pattern("PAGER=blah git log --oneline"),
            Some("^PAGER=blah\\s+git\\s+log(\\s|$)".to_string())
        );
        assert_eq!(
            extract_terminal_pattern("A=1 B=2 git log"),
            Some("^A=1\\s+B=2\\s+git\\s+log(\\s|$)".to_string())
        );
        assert_eq!(
            extract_terminal_pattern("PAGER='less -R' git log"),
            Some("^PAGER='less -R'\\s+git\\s+log(\\s|$)".to_string())
        );

        // Path-like commands are rejected
        assert_eq!(extract_terminal_pattern("./script.sh arg"), None);
        assert_eq!(extract_terminal_pattern("/usr/bin/python arg"), None);
        assert_eq!(extract_terminal_pattern("PAGER=blah ./script.sh arg"), None);
    }

    #[test]
    fn test_extract_terminal_pattern_display() {
        assert_eq!(
            extract_terminal_pattern_display("cargo build --release"),
            Some("cargo build".to_string())
        );
        assert_eq!(
            extract_terminal_pattern_display("cargo test -p search"),
            Some("cargo test".to_string())
        );
        assert_eq!(
            extract_terminal_pattern_display("npm install"),
            Some("npm install".to_string())
        );
        assert_eq!(
            extract_terminal_pattern_display("ls -la"),
            Some("ls".to_string())
        );
        assert_eq!(
            extract_terminal_pattern_display("ls"),
            Some("ls".to_string())
        );
        assert_eq!(
            extract_terminal_pattern_display("PAGER=blah   git   log --oneline"),
            Some("PAGER=blah   git   log".to_string())
        );
        assert_eq!(
            extract_terminal_pattern_display("PAGER='less -R' git log"),
            Some("PAGER='less -R' git log".to_string())
        );
    }

    #[test]
    fn test_terminal_pattern_regex_normalizes_whitespace() {
        let pattern = extract_terminal_pattern("PAGER=blah   git   log --oneline")
            .expect("expected terminal pattern");
        let regex = regex::Regex::new(&pattern).expect("expected valid regex");

        assert!(regex.is_match("PAGER=blah git log"));
        assert!(regex.is_match("PAGER=blah    git    log --stat"));
    }

    #[test]
    fn test_extract_terminal_pattern_skips_redirects_before_subcommand() {
        assert_eq!(
            extract_terminal_pattern("git 2>/dev/null log --oneline"),
            Some("^git\\s+log(\\s|$)".to_string())
        );
        assert_eq!(
            extract_terminal_pattern_display("git 2>/dev/null log --oneline"),
            Some("git 2>/dev/null log".to_string())
        );

        assert_eq!(
            extract_terminal_pattern("rm --force foo"),
            Some("^rm\\b".to_string())
        );
    }

    #[test]
    fn test_extract_all_terminal_patterns_pipeline() {
        assert_eq!(
            extract_all_terminal_patterns("cargo test 2>&1 | tail"),
            vec![
                PermissionPattern {
                    pattern: "^cargo\\s+test(\\s|$)".to_string(),
                    display_name: "cargo test".to_string(),
                },
                PermissionPattern {
                    pattern: "^tail\\b".to_string(),
                    display_name: "tail".to_string(),
                },
            ]
        );
    }

    #[test]
    fn test_extract_all_terminal_patterns_with_path_commands() {
        assert_eq!(
            extract_all_terminal_patterns("./script.sh | grep foo"),
            vec![PermissionPattern {
                pattern: "^grep\\s+foo(\\s|$)".to_string(),
                display_name: "grep foo".to_string(),
            }]
        );
    }

    #[test]
    fn test_extract_all_terminal_patterns_all_paths() {
        assert_eq!(extract_all_terminal_patterns("./a.sh | /usr/bin/b"), vec![]);
    }

    #[test]
    fn test_extract_path_pattern() {
        assert_eq!(
            extract_path_pattern("/Users/alice/project/src/main.rs"),
            Some("^/Users/alice/project/src/".to_string())
        );
        assert_eq!(
            extract_path_pattern("src/lib.rs"),
            Some("^src/".to_string())
        );
        assert_eq!(extract_path_pattern("file.txt"), None);
        assert_eq!(extract_path_pattern("/file.txt"), None);
    }

    #[test]
    fn test_extract_path_pattern_display() {
        assert_eq!(
            extract_path_pattern_display("/Users/alice/project/src/main.rs"),
            Some("/Users/alice/project/src/".to_string())
        );
        assert_eq!(
            extract_path_pattern_display("src/lib.rs"),
            Some("src/".to_string())
        );
    }

    #[test]
    fn test_extract_url_pattern() {
        assert_eq!(
            extract_url_pattern("https://github.com/user/repo"),
            Some("^https?://github\\.com".to_string())
        );
        assert_eq!(
            extract_url_pattern("http://example.com/path?query=1"),
            Some("^https?://example\\.com".to_string())
        );
        assert_eq!(extract_url_pattern("not a url"), None);
    }

    #[test]
    fn test_extract_url_pattern_display() {
        assert_eq!(
            extract_url_pattern_display("https://github.com/user/repo"),
            Some("github.com".to_string())
        );
        assert_eq!(
            extract_url_pattern_display("http://api.example.com/v1/users"),
            Some("api.example.com".to_string())
        );
    }

    #[test]
    fn test_dashes_are_not_escaped() {
        assert_eq!(
            extract_terminal_pattern("git-lfs pull"),
            Some("^git-lfs\\s+pull(\\s|$)".to_string())
        );
        assert_eq!(
            extract_url_pattern("https://typescript-eslint.io/rules/no-unused-vars"),
            Some("^https?://typescript-eslint\\.io".to_string())
        );
        assert_eq!(
            extract_path_pattern("/my-project/sub-dir/file.rs"),
            Some("^/my-project/sub-dir/".to_string())
        );
    }

    #[test]
    fn test_special_chars_are_escaped() {
        assert_eq!(
            extract_path_pattern("/path/with (parens)/file.txt"),
            Some("^/path/with \\(parens\\)/".to_string())
        );
        assert_eq!(
            extract_url_pattern("https://test.example.com/path"),
            Some("^https?://test\\.example\\.com".to_string())
        );
    }

    #[test]
    fn test_extract_copy_move_pattern_same_directory() {
        assert_eq!(
            extract_copy_move_pattern(
                "/Users/alice/project/src/old.rs\n/Users/alice/project/src/new.rs"
            ),
            Some("^/Users/alice/project/src/".to_string())
        );
    }

    #[test]
    fn test_extract_copy_move_pattern_sibling_directories() {
        assert_eq!(
            extract_copy_move_pattern(
                "/Users/alice/project/src/old.rs\n/Users/alice/project/dst/new.rs"
            ),
            Some("^/Users/alice/project/".to_string())
        );
    }

    #[test]
    fn test_extract_copy_move_pattern_no_common_prefix() {
        assert_eq!(
            extract_copy_move_pattern("/home/file.txt\n/tmp/file.txt"),
            None
        );
    }

    #[test]
    fn test_extract_copy_move_pattern_relative_paths() {
        assert_eq!(
            extract_copy_move_pattern("src/old.rs\nsrc/new.rs"),
            Some("^src/".to_string())
        );
    }

    #[test]
    fn test_extract_copy_move_pattern_display() {
        assert_eq!(
            extract_copy_move_pattern_display(
                "/Users/alice/project/src/old.rs\n/Users/alice/project/dst/new.rs"
            ),
            Some("/Users/alice/project/".to_string())
        );
    }

    #[test]
    fn test_extract_copy_move_pattern_no_arrow() {
        assert_eq!(extract_copy_move_pattern("just/a/path.rs"), None);
        assert_eq!(extract_copy_move_pattern_display("just/a/path.rs"), None);
    }
}