// Code for annotating snippets.

use crate::Level;

#[derive(Clone, Debug, PartialOrd, Ord, PartialEq, Eq)]
pub struct Line {
    pub line_index: usize,
    pub annotations: Vec<Annotation>,
}

#[derive(Clone, Debug, PartialOrd, Ord, PartialEq, Eq)]
pub struct MultilineAnnotation {
    pub depth: usize,
    pub line_start: usize,
    pub line_end: usize,
    pub start_col: usize,
    pub end_col: usize,
    pub is_primary: bool,
    pub label: Option<String>,
    pub overlaps_exactly: bool,
}

impl MultilineAnnotation {
    pub fn increase_depth(&mut self) {
        self.depth += 1;
    }

    /// Compare two `MultilineAnnotation`s considering only the `Span` they cover.
    pub fn same_span(&self, other: &MultilineAnnotation) -> bool {
        self.line_start == other.line_start
            && self.line_end == other.line_end
            && self.start_col == other.start_col
            && self.end_col == other.end_col
    }

    pub fn as_start(&self) -> Annotation {
        Annotation {
            start_col: self.start_col,
            end_col: self.start_col + 1,
            is_primary: self.is_primary,
            label: None,
            annotation_type: AnnotationType::MultilineStart(self.depth),
        }
    }

    pub fn as_end(&self) -> Annotation {
        Annotation {
            start_col: self.end_col.saturating_sub(1),
            end_col: self.end_col,
            is_primary: self.is_primary,
            label: self.label.clone(),
            annotation_type: AnnotationType::MultilineEnd(self.depth),
        }
    }

    pub fn as_line(&self) -> Annotation {
        Annotation {
            start_col: 0,
            end_col: 0,
            is_primary: self.is_primary,
            label: None,
            annotation_type: AnnotationType::MultilineLine(self.depth),
        }
    }
}

#[derive(Clone, Debug, PartialOrd, Ord, PartialEq, Eq)]
pub enum AnnotationType {
    /// Annotation under a single line of code
    Singleline,

    /// Annotation enclosing the first and last character of a multiline span
    Multiline(MultilineAnnotation),

    // The Multiline type above is replaced with the following three in order
    // to reuse the current label drawing code.
    //
    // Each of these corresponds to one part of the following diagram:
    //
    //     x |   foo(1 + bar(x,
    //       |  _________^              < MultilineStart
    //     x | |             y),        < MultilineLine
    //       | |______________^ label   < MultilineEnd
    //     x |       z);
    /// Annotation marking the first character of a fully shown multiline span
    MultilineStart(usize),
    /// Annotation marking the last character of a fully shown multiline span
    MultilineEnd(usize),
    /// Line at the left enclosing the lines of a fully shown multiline span
    // Just a placeholder for the drawing algorithm, to know that it shouldn't skip the first 4
    // and last 2 lines of code. The actual line is drawn in `emit_message_default` and not in
    // `draw_multiline_line`.
    MultilineLine(usize),
}

#[derive(Clone, Debug, PartialOrd, Ord, PartialEq, Eq)]
pub struct Annotation {
    /// Start column, 0-based indexing -- counting *characters*, not
    /// utf-8 bytes. Note that it is important that this field goes
    /// first, so that when we sort, we sort orderings by start
    /// column.
    pub start_col: usize,

    /// End column within the line (exclusive)
    pub end_col: usize,

    /// Is this annotation derived from primary span
    pub is_primary: bool,

    /// Optional label to display adjacent to the annotation.
    pub label: Option<String>,

    /// Is this a single line, multiline or multiline span minimized down to a
    /// smaller span.
    pub annotation_type: AnnotationType,
}

impl Annotation {
    /// Whether this annotation is a vertical line placeholder.
    pub fn is_line(&self) -> bool {
        matches!(self.annotation_type, AnnotationType::MultilineLine(_))
    }

    pub fn is_multiline(&self) -> bool {
        matches!(self.annotation_type,
            AnnotationType::Multiline(_)
            | AnnotationType::MultilineStart(_)
            | AnnotationType::MultilineLine(_)
            | AnnotationType::MultilineEnd(_))
    }

    pub fn len(&self) -> usize {
        // Account for usize underflows
        if self.end_col > self.start_col {
            self.end_col - self.start_col
        } else {
            self.start_col - self.end_col
        }
    }

    pub fn has_label(&self) -> bool {
        if let Some(ref label) = self.label {
            // Consider labels with no text as effectively not being there
            // to avoid weird output with unnecessary vertical lines, like:
            //
            //     X | fn foo(x: u32) {
            //       | -------^------
            //       | |      |
            //       | |
            //       |
            //
            // Note that this would be the complete output users would see.
            !label.is_empty()
        } else {
            false
        }
    }

    pub fn takes_space(&self) -> bool {
        // Multiline annotations always have to keep vertical space.
        match self.annotation_type {
            AnnotationType::MultilineStart(_) | AnnotationType::MultilineEnd(_) => true,
            _ => false,
        }
    }
}

#[derive(Debug)]
pub struct StyledString {
    pub text: String,
    pub style: Style,
}

#[derive(Copy, Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
pub enum Style {
    MainHeaderMsg,
    HeaderMsg,
    LineAndColumn,
    LineNumber,
    Quotation,
    UnderlinePrimary,
    UnderlineSecondary,
    LabelPrimary,
    LabelSecondary,
    NoStyle,
    Level(Level),
    Highlight,
}
