use ariadne::{Color, Fmt};
use ariadne::{Report, ReportKind};
use rand::TryRng;
use yansi::Paint;
use std::cell::RefCell;
use std::collections::{HashMap, VecDeque};
use std::fmt::Display;

use crate::procio::RedirGuard;
use crate::{
  parse::lex::{Span, SpanSource},
  prelude::*,
};

pub type ShResult<T> = Result<T, ShErr>;

pub struct ColorRng {
  last_color: Option<Color>,
}

impl ColorRng {
  fn get_colors() -> &'static [Color] {
    &[
      Color::Red,
      Color::Cyan,
      Color::Blue,
      Color::Green,
      Color::Yellow,
      Color::Magenta,
      Color::Fixed(208), // orange
      Color::Fixed(39),  // deep sky blue
      Color::Fixed(170), // orchid / magenta-pink
      Color::Fixed(76),  // chartreuse
      Color::Fixed(51),  // aqua
      Color::Fixed(226), // bright yellow
      Color::Fixed(99),  // slate blue
      Color::Fixed(214), // light orange
      Color::Fixed(48),  // spring green
      Color::Fixed(201), // hot pink
      Color::Fixed(81),  // steel blue
      Color::Fixed(220), // gold
      Color::Fixed(105), // medium purple
    ]
  }

  pub fn last_color(&mut self) -> Color {
    if let Some(color) = self.last_color.take() {
      color
    } else {
      let color = self.next().unwrap_or(Color::White);
      self.last_color = Some(color);
      color
    }
  }
}

impl Iterator for ColorRng {
  type Item = Color;
  fn next(&mut self) -> Option<Self::Item> {
    let colors = Self::get_colors();
    let idx = rand::rngs::SysRng.try_next_u32().ok()? as usize % colors.len();
    Some(colors[idx])
  }
}

thread_local! {
  static COLOR_RNG: RefCell<ColorRng> = const { RefCell::new(ColorRng { last_color: None }) };
}

pub fn next_color() -> Color {
  COLOR_RNG.with(|rng| {
    let color = rng.borrow_mut().next().unwrap();
    rng.borrow_mut().last_color = Some(color);
    color
  })
}

pub fn last_color() -> Color {
  COLOR_RNG.with(|rng| rng.borrow_mut().last_color())
}

pub fn clear_color() {
  COLOR_RNG.with(|rng| rng.borrow_mut().last_color = None);
}

pub trait ShResultExt {
  fn blame(self, span: Span) -> Self;
  fn try_blame(self, span: Span) -> Self;
  fn promote_err(self, span: Span) -> Self;
  fn is_flow_control(&self) -> bool;
}

impl<T> ShResultExt for Result<T, ShErr> {
  /// Blame a span for an error
  fn blame(self, new_span: Span) -> Self {
    self.map_err(|e| e.blame(new_span))
  }
  /// Blame a span if no blame has been assigned yet
  fn try_blame(self, new_span: Span) -> Self {
    self.map_err(|e| e.try_blame(new_span))
  }
  fn promote_err(self, span: Span) -> Self {
    self.map_err(|e| e.promote(span))
  }
  fn is_flow_control(&self) -> bool {
    self.as_ref().is_err_and(|e| e.is_flow_control())
  }
}

#[derive(Clone, Debug)]
pub struct Note {
  main: String,
  sub_notes: Vec<Note>,
  depth: usize,
}

impl Note {
  pub fn new(main: impl Into<String>) -> Self {
    Self {
      main: main.into(),
      sub_notes: vec![],
      depth: 0,
    }
  }

  pub fn with_sub_notes(self, new_sub_notes: Vec<impl Into<String>>) -> Self {
    let Self {
      main,
      mut sub_notes,
      depth,
    } = self;
    for raw_note in new_sub_notes {
      let mut note = Note::new(raw_note);
      note.depth = self.depth + 1;
      sub_notes.push(note);
    }
    Self {
      main,
      sub_notes,
      depth,
    }
  }
}

impl Display for Note {
  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    let note = Fmt::fg("note", Color::Green);
    let main = &self.main;
    if self.depth == 0 {
      writeln!(f, "{note}: {main}")?;
    } else {
      let bar_break = Fmt::fg("-", Color::Cyan);
			let bar_break = bar_break.bold();
      let indent = "  ".repeat(self.depth);
      writeln!(f, "  {indent}{bar_break} {main}")?;
    }

    for sub_note in &self.sub_notes {
      write!(f, "{sub_note}")?;
    }
    Ok(())
  }
}

#[derive(Debug)]
pub struct ShErr {
  kind: ShErrKind,
  src_span: Option<Span>,
  labels: Vec<ariadne::Label<Span>>,
  sources: Vec<SpanSource>,
  notes: Vec<String>,

  /// If we propagate through a redirect boundary, we take ownership of
  /// the RedirGuard(s) so that redirections stay alive until the error
  /// is printed.  Multiple guards can accumulate as the error bubbles
  /// through nested redirect scopes.
  io_guards: Vec<RedirGuard>,
}

impl ShErr {
  pub fn new(kind: ShErrKind, span: Span) -> Self {
    Self {
      kind,
      src_span: Some(span),
      labels: vec![],
      sources: vec![],
      notes: vec![],
      io_guards: vec![],
    }
  }
  pub fn simple(kind: ShErrKind, msg: impl Into<String>) -> Self {
    Self {
      kind,
      src_span: None,
      labels: vec![],
      sources: vec![],
      notes: vec![msg.into()],
      io_guards: vec![],
    }
  }
  pub fn is_flow_control(&self) -> bool {
    self.kind.is_flow_control()
  }
  pub fn promote(mut self, span: Span) -> Self {
    if self.notes.is_empty() {
      return self;
    }
    let first = self.notes[0].clone();
    if self.notes.len() > 1 {
      self.notes = self.notes[1..].to_vec();
    }

    self.labeled(span, first)
  }
  pub fn with_redirs(mut self, guard: RedirGuard) -> Self {
    self.io_guards.push(guard);
    self
  }
  pub fn at(kind: ShErrKind, span: Span, msg: impl Into<String>) -> Self {
    let color = last_color(); // use last_color to ensure the same color is used for the label and the message given
    let src = span.span_source().clone();
    let msg: String = msg.into();
    Self::new(kind, span.clone()).with_label(
      src,
      ariadne::Label::new(span)
        .with_color(color)
        .with_message(msg),
    )
  }
  pub fn labeled(self, span: Span, msg: impl Into<String>) -> Self {
    let color = last_color();
    let src = span.span_source().clone();
    let msg: String = msg.into();
    self.with_label(
      src,
      ariadne::Label::new(span)
        .with_color(color)
        .with_message(msg),
    )
  }
  pub fn blame(self, span: Span) -> Self {
    let ShErr {
      kind,
      src_span: _,
      labels,
      sources,
      notes,
      io_guards,
    } = self;
    Self {
      kind,
      src_span: Some(span),
      labels,
      sources,
      notes,
      io_guards,
    }
  }
  pub fn try_blame(self, span: Span) -> Self {
    match self {
      ShErr {
        kind,
        src_span: None,
        labels,
        sources,
        notes,
        io_guards,
      } => Self {
        kind,
        src_span: Some(span),
        labels,
        sources,
        notes,
        io_guards,
      },
      _ => self,
    }
  }
  pub fn kind(&self) -> &ShErrKind {
    &self.kind
  }
  pub fn rename(mut self, name: impl Into<String>) -> Self {
    if let Some(span) = self.src_span.as_mut() {
      span.rename(name.into());
    }
    self
  }
  pub fn with_label(self, source: SpanSource, label: ariadne::Label<Span>) -> Self {
    let ShErr {
      kind,
      src_span,
      mut labels,
      mut sources,
      notes,
      io_guards,
    } = self;
    sources.push(source);
    labels.push(label);
    Self {
      kind,
      src_span,
      labels,
      sources,
      notes,
      io_guards,
    }
  }
  pub fn with_context(self, ctx: VecDeque<(SpanSource, ariadne::Label<Span>)>) -> Self {
    let ShErr {
      kind,
      src_span,
      mut labels,
      mut sources,
      notes,
      io_guards,
    } = self;
    for (src, label) in ctx {
      sources.push(src);
      labels.push(label);
    }
    Self {
      kind,
      src_span,
      labels,
      sources,
      notes,
      io_guards,
    }
  }
  pub fn with_note(self, note: impl Into<String>) -> Self {
    let ShErr {
      kind,
      src_span,
      labels,
      sources,
      mut notes,
      io_guards,
    } = self;
    notes.push(note.into());
    Self {
      kind,
      src_span,
      labels,
      sources,
      notes,
      io_guards,
    }
  }
  pub fn build_report(&self) -> Option<Report<'_, Span>> {
    let span = self.src_span.as_ref()?;
    let mut report = Report::build(ReportKind::Error, span.clone())
      .with_config(ariadne::Config::default().with_color(true));
    let msg = if self.notes.is_empty() {
      self.kind.to_string()
    } else {
      format!("{} - {}", self.kind, self.notes.first().unwrap())
    };
    report = report.with_message(msg);

    for label in self.labels.clone() {
      report = report.with_label(label);
    }
    for note in &self.notes {
      report = report.with_note(note);
    }

    Some(report.finish())
  }
  fn collect_sources(&self) -> HashMap<SpanSource, String> {
    let mut source_map = HashMap::new();
    if let Some(span) = &self.src_span {
      let src = span.span_source().clone();
      source_map
        .entry(src.clone())
        .or_insert_with(|| src.content().to_string());
    }
    for src in &self.sources {
      source_map
        .entry(src.clone())
        .or_insert_with(|| src.content().to_string());
    }
    source_map
  }
  pub fn print_error(&self) {
    let default = || {
      eprintln!("\n{}", self.kind);
      for note in &self.notes {
        eprintln!("note: {note}");
      }
    };
    let Some(report) = self.build_report() else {
      return default();
    };

    let sources = self.collect_sources();
    let cache = ariadne::FnCache::new(move |src: &SpanSource| {
      sources
        .get(src)
        .cloned()
        .ok_or_else(|| format!("Failed to fetch source '{}'", src.name()))
    });
    eprintln!();
    if report.eprint(cache).is_err() {
      default();
    }
  }
}

impl Display for ShErr {
  fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
    if self.notes.is_empty() {
      write!(f, "{}", self.kind)
    } else {
      write!(f, "{} - {}", self.kind, self.notes.first().unwrap())
    }
  }
}

impl From<std::io::Error> for ShErr {
  fn from(e: std::io::Error) -> Self {
    let msg = std::io::Error::last_os_error();
    ShErr::simple(ShErrKind::IoErr(e.kind()), msg.to_string())
  }
}

impl From<std::env::VarError> for ShErr {
  fn from(value: std::env::VarError) -> Self {
    ShErr::simple(ShErrKind::InternalErr, value.to_string())
  }
}

impl From<Errno> for ShErr {
  fn from(value: Errno) -> Self {
    ShErr::simple(ShErrKind::Errno(value), value.to_string())
  }
}

#[derive(Debug, Clone)]
pub enum ShErrKind {
  IoErr(io::ErrorKind),
  InvalidOpt,
  SyntaxErr,
  ParseErr,
  InternalErr,
  ExecFail,
  HistoryReadErr,
  ResourceLimitExceeded,
  BadPermission,
  Errno(Errno),
  NotFound,
  ReadlineErr,
  ExCommand,

  // Not really errors, more like internal signals
  CleanExit(i32),
  FuncReturn(i32),
  LoopContinue(i32),
  LoopBreak(i32),
  ClearReadline,
  Null,
}

impl ShErrKind {
  pub fn is_flow_control(&self) -> bool {
    matches!(
      self,
      Self::CleanExit(_)
        | Self::FuncReturn(_)
        | Self::LoopContinue(_)
        | Self::LoopBreak(_)
        | Self::ClearReadline
    )
  }
}

impl Display for ShErrKind {
  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    let output = match self {
      Self::IoErr(e) => &format!("I/O Error: {e}"),
      Self::InvalidOpt => "Invalid option",
      Self::SyntaxErr => "Syntax Error",
      Self::ParseErr => "Parse Error",
      Self::InternalErr => "Internal Error",
      Self::HistoryReadErr => "History Parse Error",
      Self::ExecFail => "Execution Failed",
      Self::ResourceLimitExceeded => "Resource Limit Exceeded",
      Self::BadPermission => "Bad Permissions",
      Self::Errno(e) => &format!("Errno: {}", e.desc()),
      Self::NotFound => "Not Found",
      Self::CleanExit(_) => "",
      Self::FuncReturn(_) => "Syntax Error",
      Self::LoopContinue(_) => "Syntax Error",
      Self::LoopBreak(_) => "Syntax Error",
      Self::ReadlineErr => "Readline Error",
      Self::ExCommand => "Ex Command Error",
      Self::ClearReadline => "",
      Self::Null => "",
    };
    write!(f, "{output}")
  }
}