use crossterm::cursor;
use crossterm::style;
use crossterm::terminal;
use crossterm::QueueableCommand;
use parking_lot::Mutex;
use std::io::stderr;
use std::io::stdout;
use std::io::Stderr;
use std::io::Stdout;
use std::io::Write;
use std::sync::Arc;

pub enum LoggerTextItem {
  Text(String),
  HangingText { text: String, indent: u16 },
}

#[derive(PartialOrd, Ord, PartialEq, Eq)]
pub(crate) enum LoggerRefreshItemKind {
  // numbered by display order
  ProgressBars = 0,
  Selection = 1,
}

struct LoggerRefreshItem {
  kind: LoggerRefreshItemKind,
  text_items: Vec<LoggerTextItem>,
}

#[derive(Clone)]
pub struct Logger {
  output_lock: Arc<Mutex<LoggerState>>,
}

struct LoggerState {
  is_silent: bool,
  last_context_name: String,
  std_out: Stdout,
  std_err: Stderr,
  refresh_items: Vec<LoggerRefreshItem>,
  last_terminal_size: Option<(u16, u16)>,
}

impl Logger {
  pub fn new(initial_context_name: &str, is_silent: bool) -> Self {
    Logger {
      output_lock: Arc::new(Mutex::new(LoggerState {
        is_silent,
        last_context_name: initial_context_name.to_string(),
        std_out: stdout(),
        std_err: stderr(),
        refresh_items: Vec::new(),
        last_terminal_size: None,
      })),
    }
  }

  pub fn log(&self, text: &str, context_name: &str) {
    let mut state = self.output_lock.lock();
    if state.is_silent {
      return;
    }
    self.inner_log(&mut state, true, text, context_name);
  }

  pub fn log_bypass_silent(&self, text: &str, context_name: &str) {
    let mut state = self.output_lock.lock();
    self.inner_log(&mut state, true, text, context_name);
  }

  pub fn log_err(&self, text: &str, context_name: &str) {
    let mut state = self.output_lock.lock();
    self.inner_log(&mut state, false, text, context_name);
  }

  pub fn log_text_items(&self, text_items: &[LoggerTextItem], context_name: &str, terminal_width: Option<u16>) {
    let text = render_text_items_with_width(text_items, terminal_width);
    self.log(&text, context_name);
  }

  fn inner_log(&self, state: &mut LoggerState, is_std_out: bool, text: &str, context_name: &str) {
    if !state.refresh_items.is_empty() {
      self.inner_queue_clear_previous_draws(state);
    }

    let mut output_text = String::new();
    if state.last_context_name != context_name {
      output_text.push_str(&format!("[{}]\n", context_name));
      state.last_context_name = context_name.to_string();
    }

    output_text.push_str(text);

    // only add a newline if the logged text does not end with one
    if !output_text.ends_with('\n') {
      output_text.push('\n');
    }

    if is_std_out {
      state.std_out.queue(style::Print(output_text)).unwrap();
    } else {
      state.std_err.queue(style::Print(output_text)).unwrap();
    }

    if !state.refresh_items.is_empty() {
      self.inner_queue_draw_items(state);
    }

    if is_std_out {
      state.std_out.flush().unwrap();
      if !state.refresh_items.is_empty() {
        state.std_err.flush().unwrap();
      }
    } else {
      state.std_err.flush().unwrap();
    }
  }

  pub(crate) fn set_refresh_item(&self, kind: LoggerRefreshItemKind, text_items: Vec<LoggerTextItem>) {
    self.with_update_refresh_items(move |refresh_items| match refresh_items.binary_search_by(|i| i.kind.cmp(&kind)) {
      Ok(pos) => {
        let mut refresh_item = refresh_items.get_mut(pos).unwrap();
        refresh_item.text_items = text_items;
      }
      Err(pos) => {
        let refresh_item = LoggerRefreshItem { kind, text_items };
        refresh_items.insert(pos, refresh_item);
      }
    });
  }

  pub(crate) fn remove_refresh_item(&self, kind: LoggerRefreshItemKind) {
    self.with_update_refresh_items(move |refresh_items| {
      if let Ok(pos) = refresh_items.binary_search_by(|i| i.kind.cmp(&kind)) {
        refresh_items.remove(pos);
      } else {
        // already removed
      }
    });
  }

  fn with_update_refresh_items(&self, update_refresh_items: impl FnOnce(&mut Vec<LoggerRefreshItem>)) {
    let mut state = self.output_lock.lock();

    // hide the cursor if showing a refresh item for the first time
    if state.refresh_items.is_empty() {
      state.std_err.queue(cursor::Hide).unwrap();
    }

    self.inner_queue_clear_previous_draws(&mut state);

    update_refresh_items(&mut state.refresh_items);

    self.inner_queue_draw_items(&mut state);

    // show the cursor if no longer showing a refresh item
    if state.refresh_items.is_empty() {
      state.std_err.queue(cursor::Show).unwrap();
    }
    state.std_err.flush().unwrap();
  }

  fn inner_queue_clear_previous_draws(&self, state: &mut LoggerState) {
    let terminal_width = crate::terminal::get_terminal_width().unwrap();
    let text_items = state.refresh_items.iter().map(|item| item.text_items.iter()).flatten();
    let rendered_text = render_text_items_truncated_to_height(text_items, state.last_terminal_size);
    let last_line_count = get_text_line_count(&rendered_text, terminal_width);

    if last_line_count > 0 {
      if last_line_count > 1 {
        state.std_err.queue(cursor::MoveUp(last_line_count - 1)).unwrap();
      }
      state.std_err.queue(cursor::MoveToColumn(0)).unwrap();
      state.std_err.queue(terminal::Clear(terminal::ClearType::FromCursorDown)).unwrap();
    }

    state.std_err.queue(cursor::MoveToColumn(0)).unwrap();
  }

  fn inner_queue_draw_items(&self, state: &mut LoggerState) {
    let terminal_size = crate::terminal::get_terminal_size();
    let text_items = state.refresh_items.iter().map(|item| item.text_items.iter()).flatten();
    let rendered_text = render_text_items_truncated_to_height(text_items, terminal_size);
    state.std_err.queue(style::Print(&rendered_text)).unwrap();
    state.std_err.queue(cursor::MoveToColumn(0)).unwrap();
    state.last_terminal_size = terminal_size;
  }
}

/// Renders the text items with the specified width.
pub fn render_text_items_with_width(text_items: &[LoggerTextItem], terminal_width: Option<u16>) -> String {
  render_text_items_to_lines(text_items.iter(), terminal_width).join("\n")
}

fn render_text_items_truncated_to_height<'a>(text_items: impl Iterator<Item = &'a LoggerTextItem>, terminal_size: Option<(u16, u16)>) -> String {
  let lines = render_text_items_to_lines(text_items, terminal_size.map(|(width, _)| width));
  if let Some(height) = terminal_size.map(|(_, height)| height) {
    let max_height = height as usize;
    if lines.len() > max_height {
      return lines[lines.len() - max_height..].join("\n");
    }
  }
  lines.join("\n")
}

fn render_text_items_to_lines<'a>(text_items: impl Iterator<Item = &'a LoggerTextItem>, terminal_width: Option<u16>) -> Vec<String> {
  let mut result = Vec::new();
  for (_, item) in text_items.enumerate() {
    match item {
      LoggerTextItem::Text(text) => result.extend(render_text_to_lines(text, 0, terminal_width)),
      LoggerTextItem::HangingText { text, indent } => {
        result.extend(render_text_to_lines(text, *indent, terminal_width));
      }
    }
  }
  result
}

fn render_text_to_lines(text: &str, hanging_indent: u16, terminal_width: Option<u16>) -> Vec<String> {
  let mut lines = Vec::new();
  if let Some(terminal_width) = terminal_width {
    let mut current_line = String::new();
    let mut line_width: u16 = 0;
    let mut current_whitespace = String::new();
    for token in tokenize_words(text) {
      match token {
        WordToken::Word((word, word_width)) => {
          let is_word_longer_than_line = hanging_indent + word_width > terminal_width;
          if is_word_longer_than_line {
            // break it up onto multiple lines with indentation
            if !current_whitespace.is_empty() {
              if line_width < terminal_width {
                current_line.push_str(&current_whitespace);
              }
              current_whitespace = String::new();
            }
            for c in word.chars() {
              if line_width == terminal_width {
                lines.push(current_line);
                current_line = String::new();
                current_line.push_str(&" ".repeat(hanging_indent as usize));
                line_width = hanging_indent;
              }
              current_line.push(c);
              line_width += 1;
            }
          } else {
            if line_width + word_width > terminal_width {
              lines.push(current_line);
              current_line = String::new();
              current_line.push_str(&" ".repeat(hanging_indent as usize));
              line_width = hanging_indent;
              current_whitespace = String::new();
            }
            if !current_whitespace.is_empty() {
              current_line.push_str(&current_whitespace);
              current_whitespace = String::new();
            }
            current_line.push_str(word);
            line_width += word_width;
          }
        }
        WordToken::WhiteSpace(space_char) => {
          current_whitespace.push(space_char);
          line_width += 1;
        }
        WordToken::NewLine => {
          lines.push(current_line);
          current_line = String::new();
          line_width = 0;
        }
      }
    }
    if !current_line.is_empty() {
      lines.push(current_line);
    }
  } else {
    for line in text.lines() {
      lines.push(line.to_string());
    }
  }
  lines
}

enum WordToken<'a> {
  Word((&'a str, u16)),
  WhiteSpace(char),
  NewLine,
}

fn tokenize_words(text: &str) -> Vec<WordToken> {
  // todo: how to write an iterator version?
  let mut start_index = 0;
  let mut tokens = Vec::new();
  let mut word_width = 0;
  for (index, c) in text.char_indices() {
    if c.is_whitespace() || c == '\n' {
      if word_width > 0 {
        tokens.push(WordToken::Word((&text[start_index..index], word_width)));
        word_width = 0;
      }

      if c == '\n' {
        tokens.push(WordToken::NewLine);
      } else {
        tokens.push(WordToken::WhiteSpace(c));
      }

      start_index = index + c.len_utf8(); // start at next char
    } else if !c.is_ascii_control() {
      word_width += 1;
    }
  }
  if word_width > 0 {
    tokens.push(WordToken::Word((&text[start_index..text.len()], word_width)));
  }
  tokens
}

fn get_text_line_count(text: &str, terminal_width: u16) -> u16 {
  let mut line_count: u16 = 0;
  let mut line_width: u16 = 0;
  for c in text.chars() {
    if c.is_ascii_control() && !c.is_ascii_whitespace() {
      // ignore
    } else if c == '\n' {
      line_count += 1;
      line_width = 0;
    } else if line_width == terminal_width {
      line_width = 0;
      line_count += 1;
    } else {
      line_width += 1;
    }
  }
  line_count + 1
}