use std::error::Error;
use std::fmt;
use std::hash::Hasher;
use std::num::{NonZeroU8, NonZeroU16, ParseIntError};
use std::str::FromStr;

use serde::{Deserialize, Serialize};
use unicode_width::UnicodeWidthChar;

use ruff_cache::{CacheKey, CacheKeyHasher};
use ruff_macros::CacheKey;
use ruff_text_size::TextSize;

/// The length of a line of text that is considered too long.
///
/// The allowed range of values is 1..=65535
#[derive(Clone, Copy, Debug, Eq, PartialEq, serde::Serialize)]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
pub struct LineLength(NonZeroU16);

impl LineLength {
    /// Maximum allowed value for a valid [`LineLength`]
    pub const MAX: u16 = u16::MAX;

    /// Return the numeric value for this [`LineLength`]
    pub fn value(&self) -> u16 {
        self.0.get()
    }

    pub fn text_len(&self) -> TextSize {
        TextSize::from(u32::from(self.value()))
    }
}

impl Default for LineLength {
    fn default() -> Self {
        Self(NonZeroU16::new(88).unwrap())
    }
}

impl fmt::Display for LineLength {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::Display::fmt(&self.0, f)
    }
}

impl<'de> serde::Deserialize<'de> for LineLength {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        let value = i64::deserialize(deserializer)?;

        u16::try_from(value)
            .ok()
            .and_then(|u16_value| Self::try_from(u16_value).ok())
            .ok_or_else(|| {
                serde::de::Error::custom(format!(
                    "line-length must be between 1 and {} (got {value})",
                    Self::MAX,
                ))
            })
    }
}

impl CacheKey for LineLength {
    fn cache_key(&self, state: &mut CacheKeyHasher) {
        state.write_u16(self.0.get());
    }
}

/// Error type returned when parsing a [`LineLength`] from a string fails
pub enum ParseLineWidthError {
    /// The string could not be parsed as a valid [u16]
    ParseError(ParseIntError),
    /// The [u16] value of the string is not a valid [`LineLength`]
    TryFromIntError(LineLengthFromIntError),
}

impl std::fmt::Debug for ParseLineWidthError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        std::fmt::Display::fmt(self, f)
    }
}

impl std::fmt::Display for ParseLineWidthError {
    fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            ParseLineWidthError::ParseError(err) => std::fmt::Display::fmt(err, fmt),
            ParseLineWidthError::TryFromIntError(err) => std::fmt::Display::fmt(err, fmt),
        }
    }
}

impl Error for ParseLineWidthError {}

impl FromStr for LineLength {
    type Err = ParseLineWidthError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let value = u16::from_str(s).map_err(ParseLineWidthError::ParseError)?;
        let value = Self::try_from(value).map_err(ParseLineWidthError::TryFromIntError)?;
        Ok(value)
    }
}

/// Error type returned when converting a u16 to a [`LineLength`] fails
#[derive(Clone, Copy, Debug)]
pub struct LineLengthFromIntError(pub u16);

impl TryFrom<u16> for LineLength {
    type Error = LineLengthFromIntError;

    fn try_from(value: u16) -> Result<Self, Self::Error> {
        match NonZeroU16::try_from(value) {
            Ok(value) => Ok(LineLength(value)),
            Err(_) => Err(LineLengthFromIntError(value)),
        }
    }
}

impl std::fmt::Display for LineLengthFromIntError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        writeln!(
            f,
            "The line width must be a value between 1 and {}.",
            LineLength::MAX
        )
    }
}

impl From<LineLength> for u16 {
    fn from(value: LineLength) -> Self {
        value.0.get()
    }
}

impl From<LineLength> for NonZeroU16 {
    fn from(value: LineLength) -> Self {
        value.0
    }
}

/// A measure of the width of a line of text.
///
/// This is used to determine if a line is too long.
/// It should be compared to a [`LineLength`].
#[derive(Clone, Copy, Debug)]
pub struct LineWidthBuilder {
    /// The width of the line.
    width: usize,
    /// The column of the line.
    /// This is used to calculate the width of tabs.
    column: usize,
    /// The tab size to use when calculating the width of tabs.
    tab_size: IndentWidth,
}

impl Default for LineWidthBuilder {
    fn default() -> Self {
        Self::new(IndentWidth::default())
    }
}

impl PartialEq for LineWidthBuilder {
    fn eq(&self, other: &Self) -> bool {
        self.width == other.width
    }
}

impl Eq for LineWidthBuilder {}

impl PartialOrd for LineWidthBuilder {
    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
        Some(self.cmp(other))
    }
}

impl Ord for LineWidthBuilder {
    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
        self.width.cmp(&other.width)
    }
}

impl LineWidthBuilder {
    pub fn get(&self) -> usize {
        self.width
    }

    /// Creates a new `LineWidth` with the given tab size.
    pub fn new(tab_size: IndentWidth) -> Self {
        LineWidthBuilder {
            width: 0,
            column: 0,
            tab_size,
        }
    }

    fn update(mut self, chars: impl Iterator<Item = char>) -> Self {
        let tab_size: usize = self.tab_size.as_usize();
        for c in chars {
            match c {
                '\t' => {
                    let tab_offset = tab_size - (self.column % tab_size);
                    self.width += tab_offset;
                    self.column += tab_offset;
                }
                '\n' | '\r' => {
                    self.width = 0;
                    self.column = 0;
                }
                _ => {
                    self.width += c.width().unwrap_or(0);
                    self.column += 1;
                }
            }
        }
        self
    }

    /// Adds the given text to the line width.
    #[must_use]
    pub fn add_str(self, text: &str) -> Self {
        self.update(text.chars())
    }

    /// Adds the given character to the line width.
    #[must_use]
    pub fn add_char(self, c: char) -> Self {
        self.update(std::iter::once(c))
    }

    /// Adds the given width to the line width.
    /// Also adds the given width to the column.
    /// It is generally better to use [`LineWidthBuilder::add_str`] or [`LineWidthBuilder::add_char`].
    /// The width and column should be the same for the corresponding text.
    /// Currently, this is only used to add spaces.
    #[must_use]
    pub fn add_width(mut self, width: usize) -> Self {
        self.width += width;
        self.column += width;
        self
    }
}

impl PartialEq<LineLength> for LineWidthBuilder {
    fn eq(&self, other: &LineLength) -> bool {
        self.width == (other.value() as usize)
    }
}

impl PartialOrd<LineLength> for LineWidthBuilder {
    fn partial_cmp(&self, other: &LineLength) -> Option<std::cmp::Ordering> {
        self.width.partial_cmp(&(other.value() as usize))
    }
}

/// The size of a tab.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, CacheKey)]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
pub struct IndentWidth(NonZeroU8);

impl IndentWidth {
    pub(crate) fn as_usize(self) -> usize {
        self.0.get() as usize
    }
}

impl Default for IndentWidth {
    fn default() -> Self {
        Self(NonZeroU8::new(4).unwrap())
    }
}

impl fmt::Display for IndentWidth {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::Display::fmt(&self.0, f)
    }
}

impl From<NonZeroU8> for IndentWidth {
    fn from(tab_size: NonZeroU8) -> Self {
        Self(tab_size)
    }
}

impl From<IndentWidth> for NonZeroU8 {
    fn from(value: IndentWidth) -> Self {
        value.0
    }
}
