use std::fmt;
use std::path::Path;
use std::str::FromStr;

use ruff_formatter::printer::{LineEnding, PrinterOptions, SourceMapGeneration};
use ruff_formatter::{FormatOptions, IndentStyle, IndentWidth, LineWidth};
use ruff_macros::CacheKey;
use ruff_python_ast::{self as ast, PySourceType};

/// Resolved options for formatting one individual file. The difference to `FormatterSettings`
/// is that `FormatterSettings` stores the settings for multiple files (the entire project, a subdirectory, ..)
#[derive(Clone, Debug)]
#[cfg_attr(
    feature = "serde",
    derive(serde::Serialize, serde::Deserialize),
    serde(default, deny_unknown_fields)
)]
pub struct PyFormatOptions {
    /// Whether we're in a `.py` file or `.pyi` file, which have different rules.
    source_type: PySourceType,

    /// The (minimum) Python version used to run the formatted code. This is used
    /// to determine the supported Python syntax.
    target_version: ast::PythonVersion,

    /// Specifies the indent style:
    /// * Either a tab
    /// * or a specific amount of spaces
    #[cfg_attr(feature = "serde", serde(default = "default_indent_style"))]
    indent_style: IndentStyle,

    /// The preferred line width at which the formatter should wrap lines.
    #[cfg_attr(feature = "serde", serde(default = "default_line_width"))]
    line_width: LineWidth,

    /// The visual width of a tab character.
    #[cfg_attr(feature = "serde", serde(default = "default_indent_width"))]
    indent_width: IndentWidth,

    line_ending: LineEnding,

    /// The preferred quote style to use (single vs double quotes).
    quote_style: QuoteStyle,

    /// Whether to expand lists or elements if they have a trailing comma such as `(a, b,)`.
    magic_trailing_comma: MagicTrailingComma,

    /// Should the formatter generate a source map that allows mapping source positions to positions
    /// in the formatted document.
    source_map_generation: SourceMapGeneration,

    /// Whether to format code snippets in docstrings or not.
    ///
    /// By default this is disabled (opt-in), but the plan is to make this
    /// enabled by default (opt-out) in the future.
    docstring_code: DocstringCode,

    /// The preferred line width at which the formatter should wrap lines in
    /// docstring code examples. This only has an impact when `docstring_code`
    /// is enabled.
    docstring_code_line_width: DocstringCodeLineWidth,

    /// Whether preview style formatting is enabled or not
    preview: PreviewMode,
}

fn default_line_width() -> LineWidth {
    LineWidth::try_from(88).unwrap()
}

fn default_indent_style() -> IndentStyle {
    IndentStyle::Space
}

fn default_indent_width() -> IndentWidth {
    IndentWidth::try_from(4).unwrap()
}

impl Default for PyFormatOptions {
    fn default() -> Self {
        Self {
            source_type: PySourceType::default(),
            target_version: ast::PythonVersion::default(),
            indent_style: default_indent_style(),
            line_width: default_line_width(),
            indent_width: default_indent_width(),
            quote_style: QuoteStyle::default(),
            line_ending: LineEnding::default(),
            magic_trailing_comma: MagicTrailingComma::default(),
            source_map_generation: SourceMapGeneration::default(),
            docstring_code: DocstringCode::default(),
            docstring_code_line_width: DocstringCodeLineWidth::default(),
            preview: PreviewMode::default(),
        }
    }
}

impl PyFormatOptions {
    /// Otherwise sets the defaults. Returns none if the extension is unknown
    pub fn from_extension(path: &Path) -> Self {
        Self::from_source_type(PySourceType::from(path))
    }

    pub fn from_source_type(source_type: PySourceType) -> Self {
        Self {
            source_type,
            ..Self::default()
        }
    }

    pub const fn target_version(&self) -> ast::PythonVersion {
        self.target_version
    }

    pub const fn magic_trailing_comma(&self) -> MagicTrailingComma {
        self.magic_trailing_comma
    }

    pub const fn quote_style(&self) -> QuoteStyle {
        self.quote_style
    }

    pub const fn source_type(&self) -> PySourceType {
        self.source_type
    }

    pub const fn source_map_generation(&self) -> SourceMapGeneration {
        self.source_map_generation
    }

    pub const fn line_ending(&self) -> LineEnding {
        self.line_ending
    }

    pub const fn docstring_code(&self) -> DocstringCode {
        self.docstring_code
    }

    pub const fn docstring_code_line_width(&self) -> DocstringCodeLineWidth {
        self.docstring_code_line_width
    }

    pub const fn preview(&self) -> PreviewMode {
        self.preview
    }

    #[must_use]
    pub fn with_target_version(mut self, target_version: ast::PythonVersion) -> Self {
        self.target_version = target_version;
        self
    }

    #[must_use]
    pub fn with_indent_width(mut self, indent_width: IndentWidth) -> Self {
        self.indent_width = indent_width;
        self
    }

    #[must_use]
    pub fn with_quote_style(mut self, style: QuoteStyle) -> Self {
        self.quote_style = style;
        self
    }

    #[must_use]
    pub fn with_magic_trailing_comma(mut self, trailing_comma: MagicTrailingComma) -> Self {
        self.magic_trailing_comma = trailing_comma;
        self
    }

    #[must_use]
    pub fn with_indent_style(mut self, indent_style: IndentStyle) -> Self {
        self.indent_style = indent_style;
        self
    }

    #[must_use]
    pub fn with_line_width(mut self, line_width: LineWidth) -> Self {
        self.line_width = line_width;
        self
    }

    #[must_use]
    pub fn with_line_ending(mut self, line_ending: LineEnding) -> Self {
        self.line_ending = line_ending;
        self
    }

    #[must_use]
    pub fn with_docstring_code(mut self, docstring_code: DocstringCode) -> Self {
        self.docstring_code = docstring_code;
        self
    }

    #[must_use]
    pub fn with_docstring_code_line_width(mut self, line_width: DocstringCodeLineWidth) -> Self {
        self.docstring_code_line_width = line_width;
        self
    }

    #[must_use]
    pub fn with_preview(mut self, preview: PreviewMode) -> Self {
        self.preview = preview;
        self
    }

    #[must_use]
    pub fn with_source_map_generation(mut self, source_map: SourceMapGeneration) -> Self {
        self.source_map_generation = source_map;
        self
    }
}

impl FormatOptions for PyFormatOptions {
    fn indent_style(&self) -> IndentStyle {
        self.indent_style
    }

    fn indent_width(&self) -> IndentWidth {
        self.indent_width
    }

    fn line_width(&self) -> LineWidth {
        self.line_width
    }

    fn as_print_options(&self) -> PrinterOptions {
        PrinterOptions {
            indent_width: self.indent_width,
            line_width: self.line_width,
            line_ending: self.line_ending,
            indent_style: self.indent_style,
        }
    }
}

#[derive(Copy, Clone, Debug, Default, Eq, PartialEq, CacheKey)]
#[cfg_attr(
    feature = "serde",
    derive(serde::Serialize, serde::Deserialize),
    serde(rename_all = "kebab-case")
)]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
pub enum QuoteStyle {
    Single,
    #[default]
    Double,
    Preserve,
}

impl QuoteStyle {
    pub const fn is_preserve(self) -> bool {
        matches!(self, QuoteStyle::Preserve)
    }
}

impl fmt::Display for QuoteStyle {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::Single => write!(f, "single"),
            Self::Double => write!(f, "double"),
            Self::Preserve => write!(f, "preserve"),
        }
    }
}

impl FromStr for QuoteStyle {
    type Err = &'static str;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "\"" | "double" | "Double" => Ok(Self::Double),
            "'" | "single" | "Single" => Ok(Self::Single),
            "preserve" | "Preserve" => Ok(Self::Preserve),
            // TODO: replace this error with a diagnostic
            _ => Err("Value not supported for QuoteStyle"),
        }
    }
}

#[derive(Copy, Clone, Debug, Default, CacheKey)]
#[cfg_attr(
    feature = "serde",
    derive(serde::Serialize, serde::Deserialize),
    serde(rename_all = "kebab-case")
)]
pub enum MagicTrailingComma {
    #[default]
    Respect,
    Ignore,
}

impl MagicTrailingComma {
    pub const fn is_respect(self) -> bool {
        matches!(self, Self::Respect)
    }

    pub const fn is_ignore(self) -> bool {
        matches!(self, Self::Ignore)
    }
}

impl fmt::Display for MagicTrailingComma {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::Respect => write!(f, "respect"),
            Self::Ignore => write!(f, "ignore"),
        }
    }
}

impl FromStr for MagicTrailingComma {
    type Err = &'static str;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "respect" | "Respect" => Ok(Self::Respect),
            "ignore" | "Ignore" => Ok(Self::Ignore),
            // TODO: replace this error with a diagnostic
            _ => Err("Value not supported for MagicTrailingComma"),
        }
    }
}

#[derive(Copy, Clone, Debug, Eq, PartialEq, Default, CacheKey)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[cfg_attr(feature = "serde", serde(rename_all = "lowercase"))]
pub enum PreviewMode {
    #[default]
    Disabled,

    Enabled,
}

impl PreviewMode {
    pub const fn is_enabled(self) -> bool {
        matches!(self, PreviewMode::Enabled)
    }
}

impl fmt::Display for PreviewMode {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::Disabled => write!(f, "disabled"),
            Self::Enabled => write!(f, "enabled"),
        }
    }
}

#[derive(Copy, Clone, Debug, Eq, PartialEq, Default, CacheKey)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[cfg_attr(feature = "serde", serde(rename_all = "lowercase"))]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
pub enum DocstringCode {
    #[default]
    Disabled,

    Enabled,
}

impl DocstringCode {
    pub const fn is_enabled(self) -> bool {
        matches!(self, DocstringCode::Enabled)
    }
}

impl fmt::Display for DocstringCode {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::Disabled => write!(f, "disabled"),
            Self::Enabled => write!(f, "enabled"),
        }
    }
}

#[derive(Copy, Clone, Default, Eq, PartialEq, CacheKey)]
#[cfg_attr(
    feature = "serde",
    derive(serde::Serialize, serde::Deserialize),
    serde(untagged, rename_all = "lowercase")
)]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
pub enum DocstringCodeLineWidth {
    /// Wrap docstring code examples at a fixed line width.
    #[cfg_attr(feature = "schemars", schemars(schema_with = "schema::fixed"))]
    Fixed(LineWidth),

    /// Respect the line length limit setting for the surrounding Python code.
    #[default]
    #[cfg_attr(
        feature = "serde",
        serde(deserialize_with = "deserialize_docstring_code_line_width_dynamic")
    )]
    #[cfg_attr(feature = "schemars", schemars(schema_with = "schema::dynamic"))]
    Dynamic,
}

#[cfg(feature = "schemars")]
mod schema {
    use ruff_formatter::LineWidth;
    use schemars::r#gen::SchemaGenerator;
    use schemars::schema::{Metadata, Schema, SubschemaValidation};

    /// A dummy type that is used to generate a schema for `DocstringCodeLineWidth::Dynamic`.
    pub(super) fn dynamic(_: &mut SchemaGenerator) -> Schema {
        Schema::Object(schemars::schema::SchemaObject {
            const_value: Some("dynamic".to_string().into()),
            ..Default::default()
        })
    }

    // We use a manual schema for `fixed` even thought it isn't strictly necessary according to the
    // JSON schema specification to work around a bug in Even Better TOML with `allOf`.
    // https://github.com/astral-sh/ruff/issues/15978#issuecomment-2639547101
    //
    // The only difference to the automatically derived schema is that we use `oneOf` instead of
    // `allOf`. There's no semantic difference between `allOf` and `oneOf` for single element lists.
    pub(super) fn fixed(generator: &mut SchemaGenerator) -> Schema {
        let schema = generator.subschema_for::<LineWidth>();
        Schema::Object(schemars::schema::SchemaObject {
            metadata: Some(Box::new(Metadata {
                description: Some(
                    "Wrap docstring code examples at a fixed line width.".to_string(),
                ),
                ..Metadata::default()
            })),
            subschemas: Some(Box::new(SubschemaValidation {
                one_of: Some(vec![schema]),
                ..SubschemaValidation::default()
            })),
            ..Default::default()
        })
    }
}

impl fmt::Debug for DocstringCodeLineWidth {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            DocstringCodeLineWidth::Fixed(v) => v.value().fmt(f),
            DocstringCodeLineWidth::Dynamic => "dynamic".fmt(f),
        }
    }
}

impl fmt::Display for DocstringCodeLineWidth {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::Fixed(width) => width.fmt(f),
            Self::Dynamic => write!(f, "dynamic"),
        }
    }
}

/// Responsible for deserializing the `DocstringCodeLineWidth::Dynamic`
/// variant.
fn deserialize_docstring_code_line_width_dynamic<'de, D>(d: D) -> Result<(), D::Error>
where
    D: serde::Deserializer<'de>,
{
    use serde::{Deserialize, de::Error};

    let value = String::deserialize(d)?;
    match &*value {
        "dynamic" => Ok(()),
        s => Err(D::Error::invalid_value(
            serde::de::Unexpected::Str(s),
            &"dynamic",
        )),
    }
}