use std::collections::hash_map::DefaultHasher;
use std::hash::{Hash, Hasher};
use std::path::PathBuf;

pub fn compute_content_hash(content: &str, hasher: &mut DefaultHasher) -> u64 {
    content.hash(hasher);
    hasher.finish()
}

#[derive(Clone)]
pub struct Tab {
    pub content: String,
    pub original_content_hash: u64,
    pub last_content_hash: u64,
    pub file_path: Option<PathBuf>,
    pub is_modified: bool,
    pub title: String,
    pub hasher: DefaultHasher,
}

impl Tab {
    pub fn new_empty(tab_number: usize) -> Self {
        let content = String::new();
        let mut hasher = DefaultHasher::new();
        let hash = compute_content_hash(&content, &mut hasher);
        Self {
            original_content_hash: hash,
            last_content_hash: hash,
            content,
            file_path: None,
            is_modified: false,
            title: format!("new_{tab_number}"),
            hasher,
        }
    }

    pub fn new_with_file(content: String, file_path: PathBuf) -> Self {
        let title = file_path
            .file_name()
            .and_then(|n| n.to_str())
            .unwrap_or("Untitled")
            .to_string();

        let mut hasher = DefaultHasher::new();
        let hash = compute_content_hash(&content, &mut hasher);
        Self {
            original_content_hash: hash,
            last_content_hash: hash,
            content,
            file_path: Some(file_path),
            is_modified: false,
            title,
            hasher,
        }
    }

    pub fn get_display_title(&self) -> String {
        let modified_indicator = if self.is_modified { "*" } else { "" };
        format!("{}{}", self.title, modified_indicator)
    }

    pub fn update_modified_state(&mut self) {
        if self.title.starts_with("new_") {
            self.is_modified = !self.content.is_empty();
        } else {
            let current_hash = compute_content_hash(&self.content, &mut self.hasher);
            self.is_modified = current_hash != self.last_content_hash;
            self.last_content_hash = current_hash;
        }
    }

    pub fn mark_as_saved(&mut self) {
        self.original_content_hash = compute_content_hash(&self.content, &mut self.hasher);
        self.last_content_hash = self.original_content_hash;
        self.is_modified = false;
    }
}