use std::{
    fmt::{Debug, Display},
    rc::Rc,
    sync::{atomic::AtomicU32, Arc},
};

use line_span::LineSpans;

#[cfg(feature = "parse")]
use crate::parsing::Source;
use crate::theme::ThemeGen;

pub mod themes;

#[derive(Clone, Copy, Debug)]
pub struct SourcePos(pub(crate) usize);
impl SourcePos {
    pub fn pos(&self) -> usize {
        self.0
    }
}

#[derive(Clone, Debug)]
pub struct SourceRange {
    in_file: Arc<Source>,
    start: SourcePos,
    end: SourcePos,
}
impl From<(SourcePos, SourcePos, &Arc<Source>)> for SourceRange {
    fn from(value: (SourcePos, SourcePos, &Arc<Source>)) -> Self {
        SourceRange {
            in_file: Arc::clone(value.2),
            start: value.0,
            end: value.1,
        }
    }
}
impl SourceRange {
    pub fn start(&self) -> SourcePos {
        self.start
    }
    pub fn end(&self) -> SourcePos {
        self.end
    }
    pub fn in_file(&self) -> &Arc<Source> {
        &self.in_file
    }
}
/// To `Display` this, use one of the `display` methods to get a struct with some configuration options.
/// The `Debug` impl of this is the same as `Display`ing `this.display_term()` or `this.display_notheme()`, depending on if the `ecolor-term` feature is enabled or not.
/// Since this may use ansi color codes, it should only be used when printing to a terminal, which is why `CheckError` itself has no `Display` implementation, only this one for `Debug`.
#[derive(Clone)]
pub struct CheckError(pub Vec<CheckErrorComponent>);

#[derive(Clone, Copy)]
pub enum EColor {
    Indent(u32),

    UnknownVariable,
    WhitespaceAfterHashtag,
    HashUnknown,
    HashIncludeCantLoadFile,
    HashIncludeNotAString,
    HashIncludeErrorInIncludedFile,
    BackslashEscapeUnknown,
    BackslashEscapeEOF,
    StringEOF,
    TypeEOF,
    /// `&[Int/String` (notice the missing `]`)
    BracketedRefTypeNoClosingBracket,
    IfConditionNotBool,
    ChainWithNonFunction,
    Function,
    FunctionArgument,
    InitFrom,
    InitTo,
    AssignFrom,
    AssignTo,
    AssignTargetNonReference,
    AsTypeStatementWithTooBroadType,
    AsTypeTypeAnnotation,
    BadCharInTupleType,
    BadCharInFunctionType,
    BadTypeFromParsed,
    TypeAnnotationNoClosingBracket,
    TryBadSyntax,
    TryNoFunctionFound,
    TryNotAFunction,
    TryUnusedFunction1,
    TryUnusedFunction2,
    CustomTypeTestFailed,

    StacktraceDescend,
    StacktraceDescendHashInclude,

    MaximumRuntimeExceeded,

    InCodePositionLine,
}

pub trait ETheme: ThemeGen<C = EColor, T = String> {}
impl<T: ThemeGen<C = EColor, T = String>> ETheme for T {}

pub fn colorize_str(
    message: &Vec<(String, Option<EColor>)>,
    theme: &(impl ETheme + ?Sized),
) -> String {
    let mut t = String::new();
    for (text, color) in message {
        if let Some(color) = *color {
            theme.color(text, color, &mut t)
        } else {
            theme.nocolor(text, &mut t)
        }
    }
    t
}

#[derive(Clone)]
pub enum CheckErrorComponent {
    Message(Vec<(String, Option<EColor>)>),
    Error(CheckError),
    ErrorWithDifferentSource(CheckError),
    Source(Vec<(SourceRange, Option<EColor>)>),
}
pub struct CheckErrorHRConfig {
    color_index_ptr: Rc<AtomicU32>,
    color_index: u32,
    theme: Rc<dyn ETheme>,
    is_inner: bool,
    style: u8,
    idt_start: String,
    idt_default: String,
    idt_end: String,
    idt_single: String,
    /// if true, shows "original" source code, if false, shows source with comments removed (this is what the parser uses internally)
    show_comments: bool,
}
type BorderCharsSet = [[&'static str; 4]; 3];
pub struct IndentStr<'a>(&'a str, String);
impl Display for IndentStr<'_> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}{}", self.0, self.1)
    }
}
impl CheckErrorHRConfig {
    pub const BORDER_STYLE_THIN: u8 = 0;
    pub const BORDER_STYLE_THICK: u8 = 1;
    pub const BORDER_STYLE_DOUBLE: u8 = 2;
    pub const STYLE_DEFAULT: u8 = Self::BORDER_STYLE_THIN;
    pub const STYLE_DIFFSRC: u8 = Self::BORDER_STYLE_THICK;
    const CHARS_HORIZONTAL: [&'static str; 3] = ["╶", "╴", "─"];
    const CHARS: [BorderCharsSet; 3] = [
        [
            ["╷", "┌", "┐", "┬"],
            ["│", "├", "┤", "┼"],
            ["╵", "└", "┘", "┴"],
        ],
        [
            ["╻", "┎", "┒", "┰"],
            ["┃", "┠", "┨", "╂"],
            ["╹", "┖", "┚", "┸"],
        ],
        [
            ["╦", "╓", "╖", "╥"],
            ["║", "╟", "╢", "╫"],
            ["╩", "╙", "╜", "╨"],
        ],
    ];
    fn color(&self, s: &str) -> String {
        let mut t = String::new();
        self.theme
            .color(s, EColor::Indent(self.color_index), &mut t);
        return t;
    }
    pub fn indent_start(&self, right: bool) -> IndentStr {
        IndentStr(
            &self.idt_start,
            self.color(
                Self::CHARS[self.style as usize][0][self.is_inner as usize * 2 + right as usize],
            ),
        )
    }
    pub fn indent_default(&self, right: bool) -> IndentStr {
        IndentStr(
            &self.idt_default,
            self.color(Self::CHARS[self.style as usize][1][right as usize]),
        )
    }
    pub fn indent_end(&self, right: bool) -> IndentStr {
        IndentStr(
            &self.idt_end,
            self.color(
                Self::CHARS[self.style as usize][2][self.is_inner as usize * 2 + right as usize],
            ),
        )
    }
    pub fn indent_single(&self, right: bool) -> IndentStr {
        IndentStr(
            &self.idt_single,
            self.color(if self.is_inner {
                if right {
                    Self::CHARS_HORIZONTAL[2] // left+right
                } else {
                    Self::CHARS_HORIZONTAL[1] // left only
                }
            } else {
                if right {
                    Self::CHARS_HORIZONTAL[0] // right only
                } else {
                    Self::CHARS_HORIZONTAL[1] // left only (so that there is something)
                }
            }),
        )
    }
    pub fn for_inner(&self, is_first: bool, is_last: bool, style: u8) -> Self {
        let color_index = self
            .color_index_ptr
            .fetch_add(1, std::sync::atomic::Ordering::Relaxed);
        Self {
            color_index_ptr: self.color_index_ptr.clone(),
            color_index,
            theme: Rc::clone(&self.theme),
            is_inner: true,
            style,
            idt_start: if is_first {
                self.indent_start(true)
            } else {
                self.indent_default(true)
            }
            .to_string(),
            idt_default: self.indent_default(false).to_string(),
            idt_end: if is_last {
                self.indent_end(true)
            } else {
                self.indent_default(true)
            }
            .to_string(),
            idt_single: match (is_first, is_last) {
                (false, false) => self.indent_default(true),
                (false, true) => self.indent_end(true),
                (true, false) => self.indent_start(true),
                (true, true) => self.indent_single(true),
            }
            .to_string(),
            show_comments: self.show_comments,
        }
    }
}
#[cfg(feature = "parse")]
pub struct CheckErrorDisplay<'a> {
    e: &'a CheckError,
    theme: Rc<dyn ETheme>,
    pub show_comments: bool,
}
#[cfg(feature = "parse")]
impl<'a> CheckErrorDisplay<'a> {
    pub fn show_comments(mut self, show_comments: bool) -> Self {
        self.show_comments = show_comments;
        self
    }
}
#[cfg(feature = "parse")]
impl Display for CheckErrorDisplay<'_> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        self.e.human_readable(
            f,
            &CheckErrorHRConfig {
                color_index: 0,
                color_index_ptr: Rc::new(AtomicU32::new(1)),
                theme: Rc::clone(&self.theme),
                is_inner: false,
                style: CheckErrorHRConfig::STYLE_DEFAULT,
                idt_start: String::new(),
                idt_default: String::new(),
                idt_end: String::new(),
                idt_single: String::new(),
                show_comments: self.show_comments,
            },
        )
    }
}
#[allow(unused)]
impl CheckError {
    pub fn new() -> Self {
        CheckError(vec![])
    }
    fn add(mut self, v: CheckErrorComponent) -> Self {
        self.0.push(v);
        self
    }
    fn add_mut(&mut self, v: CheckErrorComponent) -> &mut Self {
        self.0.push(v);
        self
    }
    pub(crate) fn msg_str(self, s: String) -> Self {
        self.add(CheckErrorComponent::Message(vec![(s, None)]))
    }
    pub(crate) fn msg_mut_str(&mut self, s: String) -> &mut Self {
        self.add_mut(CheckErrorComponent::Message(vec![(s, None)]))
    }
    pub(crate) fn msg(self, s: Vec<(String, Option<EColor>)>) -> Self {
        self.add(CheckErrorComponent::Message(s))
    }
    pub(crate) fn msg_mut(&mut self, s: Vec<(String, Option<EColor>)>) -> &mut Self {
        self.add_mut(CheckErrorComponent::Message(s))
    }
    pub(crate) fn err(self, e: Self) -> Self {
        self.add(CheckErrorComponent::Error(e))
    }
    pub(crate) fn err_mut(&mut self, e: Self) -> &mut Self {
        self.add_mut(CheckErrorComponent::Error(e))
    }
    pub(crate) fn err_with_diff_src(self, e: CheckError) -> Self {
        self.add(CheckErrorComponent::ErrorWithDifferentSource(e))
    }
    pub(crate) fn err_with_diff_src_mut(&mut self, e: CheckError) -> &mut Self {
        self.add_mut(CheckErrorComponent::ErrorWithDifferentSource(e))
    }
    pub(crate) fn src(self, s: Vec<(SourceRange, Option<EColor>)>) -> Self {
        self.add(CheckErrorComponent::Source(s))
    }
    pub(crate) fn src_mut(&mut self, s: Vec<(SourceRange, Option<EColor>)>) -> &mut Self {
        self.add_mut(CheckErrorComponent::Source(s))
    }
    #[cfg(feature = "parse")]
    pub fn display<'a>(&'a self, theme: impl ETheme + 'static) -> CheckErrorDisplay<'a> {
        CheckErrorDisplay {
            e: self,
            theme: Rc::new(theme),
            show_comments: true,
        }
    }
    /// Like `display`, but doesn't use any theme (doesn't colorize its output)
    #[cfg(feature = "parse")]
    pub fn display_notheme<'a>(&'a self) -> CheckErrorDisplay<'a> {
        self.display(themes::NoTheme)
    }
    /// Like `display`, but uses the default terminal theme
    #[cfg(feature = "parse")]
    #[cfg(feature = "ecolor-term")]
    pub fn display_term<'a>(&'a self) -> CheckErrorDisplay<'a> {
        self.display(themes::TermDefaultTheme)
    }
    /// will, unless empty, end in a newline
    #[cfg(feature = "parse")]
    fn human_readable(
        &self,
        f: &mut std::fmt::Formatter<'_>,
        cfg: &CheckErrorHRConfig,
    ) -> std::fmt::Result {
        const ADD_RIGHT_BITS: bool = false;
        use crate::{parsing::SourceFrom, theme::ThemeTo};

        let len = self.0.len();
        for (i, component) in self.0.iter().enumerate() {
            let is_first = i == 0;
            let is_last = i + 1 == len;
            let i = (); // to see if we use `i` anywhere else
            macro_rules! indent {
                ($s:expr, $e:expr, $right:expr) => {
                    match ($s && is_first, $e && is_last) {
                        (false, false) => cfg.indent_default($right),
                        (false, true) => cfg.indent_end($right),
                        (true, false) => cfg.indent_start($right),
                        (true, true) => cfg.indent_single($right),
                    }
                };
            }
            match component {
                CheckErrorComponent::Message(msg) => {
                    let msg = colorize_str(msg, cfg.theme.as_ref());
                    let lines = msg.lines().collect::<Vec<_>>();
                    let lc = lines.len();
                    for (i, line) in lines.into_iter().enumerate() {
                        let s = i == 0;
                        let e = i + 1 == lc;
                        writeln!(f, "{}{line}", indent!(s, e, s && ADD_RIGHT_BITS))?
                    }
                }
                CheckErrorComponent::Error(err) => {
                    let cfg = cfg.for_inner(is_first, is_last, CheckErrorHRConfig::STYLE_DEFAULT);
                    err.human_readable(f, &cfg)?;
                }
                CheckErrorComponent::ErrorWithDifferentSource(err) => {
                    let cfg = cfg.for_inner(is_first, is_last, CheckErrorHRConfig::STYLE_DIFFSRC);
                    err.human_readable(f, &cfg)?;
                }
                CheckErrorComponent::Source(highlights) => {
                    if let Some(src) = highlights.first().map(|v| v.0.in_file.as_ref()) {
                        let start = highlights.iter().map(|v| v.0.start.pos()).min();
                        let end = highlights.iter().map(|v| v.0.end.pos()).max();
                        if let (Some(start_in_line), Some(end_in_line)) = (start, end) {
                            let start = src.get_line_start(start_in_line);
                            let end = src.get_line_end(end_in_line);
                            let (start_with_comments, end_with_comments) = (
                                src.pos_in_og(start_in_line, true),
                                src.pos_in_og(end_in_line, false),
                            );
                            let (mut start, mut end) = if cfg.show_comments {
                                (src.pos_in_og(start, true), src.pos_in_og(end, false))
                            } else {
                                (start, end)
                            };
                            let mut first_line_start = 0;
                            let first_line_nr = src
                                .src_og()
                                .line_spans()
                                .take_while(|l| {
                                    if l.start() <= start_with_comments {
                                        first_line_start = l.start();
                                        true
                                    } else {
                                        false
                                    }
                                })
                                .count();
                            if cfg.show_comments && first_line_start < start {
                                start = first_line_start;
                            }
                            let mut last_line_start = 0;
                            let last_line_nr = src
                                .src_og()
                                .line_spans()
                                .take_while(|l| {
                                    if l.start() <= end_with_comments {
                                        last_line_start = l.start();
                                        if cfg.show_comments && l.end() > end {
                                            end = l.end();
                                        }
                                        true
                                    } else {
                                        false
                                    }
                                })
                                .count();
                            let src_from = match src.src_from() {
                                SourceFrom::File(path) => format!(" [{}]", path.to_string_lossy()),
                                SourceFrom::Unspecified => String::with_capacity(0),
                            };
                            if first_line_nr == last_line_nr {
                                writeln!(
                                    f,
                                    "{}{}",
                                    indent!(true, false, ADD_RIGHT_BITS),
                                    cfg.theme.color_to(
                                        &format!(
                                            "Line {first_line_nr} ({}..{}){}",
                                            start_with_comments + 1 - first_line_start,
                                            end_with_comments - last_line_start,
                                            src_from,
                                        ),
                                        EColor::InCodePositionLine
                                    )
                                )?;
                            } else {
                                writeln!(
                                    f,
                                    "{}{}",
                                    indent!(true, false, ADD_RIGHT_BITS),
                                    cfg.theme.color_to(
                                        &format!(
                                            "Lines {first_line_nr}-{last_line_nr} ({}..{}){}",
                                            start_with_comments + 1 - first_line_start,
                                            end_with_comments - last_line_start,
                                            src_from,
                                        ),
                                        EColor::InCodePositionLine
                                    )
                                )?;
                            }
                            let lines = if cfg.show_comments {
                                src.src_og()[start..end].line_spans().collect::<Vec<_>>()
                            } else {
                                src.src()[start..end].line_spans().collect::<Vec<_>>()
                            };
                            let lines_count = lines.len();
                            for (line_nr_rel, line) in lines.into_iter().enumerate() {
                                let last_line = line_nr_rel + 1 == lines_count;
                                let line_start = line.start();
                                let line_end = line.end();
                                let line = line.as_str();
                                let mut line_printed = false;
                                let mut right = 0;
                                for (highlight_index, (highlight_pos, color)) in
                                    highlights.iter().enumerate()
                                {
                                    if let Some(color) = *color {
                                        let (highlight_start, highlight_end) = if cfg.show_comments
                                        {
                                            (
                                                src.pos_in_og(highlight_pos.start.pos(), true),
                                                src.pos_in_og(highlight_pos.end.pos(), false),
                                            )
                                        } else {
                                            (highlight_pos.start.pos(), highlight_pos.end.pos())
                                        };
                                        let highlight_start = highlight_start - start;
                                        let highlight_end = highlight_end - start;
                                        if highlight_start < line_end && highlight_end > line_start
                                        {
                                            if !line_printed {
                                                // this isn't the last line (important for indent)
                                                writeln!(
                                                    f,
                                                    "{} {line}",
                                                    indent!(false, false, false)
                                                )?;
                                                line_printed = true;
                                            }
                                            // where the highlight starts in this line
                                            let hl_start =
                                                highlight_start.saturating_sub(line_start);
                                            // highlight would be further left than cursor, so we need a new line
                                            if hl_start < right {
                                                right = 0;
                                                writeln!(f)?;
                                            }
                                            // length of the highlight
                                            let hl_len = highlight_end
                                                .saturating_sub(line_start)
                                                .saturating_sub(hl_start);
                                            let hl_space = hl_start - right;
                                            let print_indent = right == 0;
                                            let hl_len = hl_len.min(line.len() - right);
                                            right += hl_space + hl_len;
                                            if print_indent && right != 0 {
                                                write!(
                                                    f,
                                                    "{} ",
                                                    indent!(
                                                        false,
                                                        // is end if last_line and
                                                        // all following highlights can be put on this line
                                                        last_line
                                                            && highlights
                                                                .iter()
                                                                .skip(highlight_index + 1)
                                                                .try_fold(
                                                                    // accumulator = end position of previous highlight
                                                                    highlight_pos.end().pos(),
                                                                    // success if all highlights start only after the previous highlight ended: a < hl.start
                                                                    |a, hl| if a < hl
                                                                        .0
                                                                        .start()
                                                                        .pos()
                                                                    {
                                                                        Some(hl.0.end().pos())
                                                                    } else {
                                                                        None
                                                                    }
                                                                )
                                                                .is_some(),
                                                        false
                                                    )
                                                )?;
                                            }
                                            write!(
                                                f,
                                                "{}{}",
                                                " ".repeat(hl_space),
                                                &cfg.theme.color_to(&"~".repeat(hl_len), color)
                                            )?;
                                        }
                                    }
                                }
                                if !line_printed {
                                    // may be last line (important for indent)
                                    writeln!(f, "{} {line}", indent!(false, last_line, false))?;
                                }
                                if right != 0 {
                                    writeln!(f)?;
                                }
                            }
                        }
                    }
                }
            }
        }
        Ok(())
    }
}
impl From<String> for CheckError {
    fn from(value: String) -> Self {
        Self::new().msg_str(value)
    }
}
impl From<&str> for CheckError {
    fn from(value: &str) -> Self {
        value.to_owned().into()
    }
}
impl Debug for CheckError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        #[cfg(feature = "ecolor-term")]
        let e = self.display_term();
        #[cfg(not(feature = "ecolor-term"))]
        let e = self.display_notheme();
        write!(f, "{e}")
    }
}