// Copyright © SixtyFPS GmbH <info@slint.dev>
// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-2.0 OR LicenseRef-Slint-Software-3.0

use i_slint_compiler::parser::SyntaxKind;
use lsp_types::{
    SemanticToken, SemanticTokenModifier, SemanticTokenType, SemanticTokens, SemanticTokensResult,
};

use crate::common::DocumentCache;

/// Give all the used types/modifier a number in an indexed array
macro_rules! declare_legend {
    ($what:ident: $ty:ty = [$($tk:ident)*]) => {
        pub const $what : &[$ty] = &[
            $(<$ty>::$tk),*
        ];
        declare_legend!{@  [ $($tk)* ], 0}
    };
    (@ [$head:ident $($tail:ident)*], $n:expr) => {
        const $head: u32 = $n;
        declare_legend!{@  [ $($tail)* ], $n + 1}
    };
    (@ [], $n:expr) => {};
}
// the id of the element
declare_legend!(LEGEND_TYPES : SemanticTokenType = [TYPE PARAMETER VARIABLE PROPERTY FUNCTION MACRO KEYWORD COMMENT STRING NUMBER OPERATOR ENUM ENUM_MEMBER]);
declare_legend!(LEGEND_MODS: SemanticTokenModifier = [DEFINITION DECLARATION]);

pub fn get_semantic_tokens(
    document_cache: &mut DocumentCache,
    text_document: &lsp_types::TextDocumentIdentifier,
) -> Option<SemanticTokensResult> {
    let doc = document_cache.get_document(&text_document.uri)?;
    let doc_node = doc.node.as_ref()?;
    let mut token = doc_node.first_token()?;
    let mut data = Vec::new();
    let mut delta_start = 0;
    let mut delta_line = 0;
    loop {
        let t_m = match token.kind() {
            SyntaxKind::Comment => Some((self::COMMENT, 0)),
            SyntaxKind::StringLiteral => Some((self::STRING, 0)),
            SyntaxKind::NumberLiteral => Some((self::NUMBER, 0)),
            SyntaxKind::ColorLiteral => Some((self::NUMBER, 0)),
            SyntaxKind::Identifier => match token.parent().kind() {
                SyntaxKind::Component => Some((self::KEYWORD, 0)),
                // the id of the element
                SyntaxKind::SubElement => Some((self::VARIABLE, 1 << self::DEFINITION)),
                SyntaxKind::RepeatedElement => Some((self::KEYWORD, 0)),
                SyntaxKind::RepeatedIndex => Some((self::VARIABLE, 1 << self::DEFINITION)),
                SyntaxKind::ConditionalElement => Some((self::KEYWORD, 0)),
                SyntaxKind::CallbackDeclaration => Some((self::KEYWORD, 0)),
                SyntaxKind::CallbackConnection => Some((self::FUNCTION, 0)),
                SyntaxKind::PropertyDeclaration => Some((self::KEYWORD, 0)),
                SyntaxKind::Function => Some((self::KEYWORD, 0)),
                SyntaxKind::PropertyAnimation => Some((self::KEYWORD, 0)),
                SyntaxKind::EnumValue => Some((self::ENUM_MEMBER, 1 << self::DEFINITION)),
                SyntaxKind::QualifiedName => match token.parent().parent()?.kind() {
                    SyntaxKind::Type => Some((self::TYPE, 0)),
                    // the base type
                    SyntaxKind::Element => Some((self::TYPE, 0)),
                    // FIXME: we should do actual lookup
                    SyntaxKind::Expression => None,
                    SyntaxKind::StatePropertyChange => Some((self::PROPERTY, 0)),
                    SyntaxKind::PropertyAnimation => Some((self::PROPERTY, 0)),
                    _ => None,
                },
                SyntaxKind::DeclaredIdentifier => {
                    match token.parent().parent()?.kind() {
                        SyntaxKind::Component => Some((self::TYPE, 1 << self::DEFINITION)),
                        SyntaxKind::RepeatedElement => {
                            Some((self::PROPERTY, 1 << self::DEFINITION))
                        }
                        SyntaxKind::CallbackDeclaration => {
                            Some((self::FUNCTION, 1 << self::DEFINITION))
                        }
                        SyntaxKind::CallbackConnection => {
                            Some((self::PARAMETER, 1 << self::DEFINITION))
                        }
                        SyntaxKind::PropertyDeclaration => {
                            Some((self::PROPERTY, 1 << self::DEFINITION))
                        }
                        SyntaxKind::State | SyntaxKind::Transition => {
                            // This is the state name, but what semantic type is that?
                            None
                        }
                        SyntaxKind::StructDeclaration => Some((self::TYPE, 1 << self::DEFINITION)),
                        SyntaxKind::EnumDeclaration => Some((self::ENUM, 1 << self::DEFINITION)),
                        SyntaxKind::PropertyChangedCallback => Some((self::PROPERTY, 0)),
                        SyntaxKind::LetStatement => Some((self::VARIABLE, 1 << self::DEFINITION)),
                        _ => None,
                    }
                }
                SyntaxKind::ChildrenPlaceholder => Some((self::MACRO, 0)),
                SyntaxKind::Binding | SyntaxKind::TwoWayBinding => Some((self::PROPERTY, 0)),
                SyntaxKind::ReturnStatement => Some((self::KEYWORD, 0)),
                SyntaxKind::LetStatement => Some((self::KEYWORD, 0)),
                SyntaxKind::AtImageUrl => Some((self::MACRO, 0)),
                SyntaxKind::AtGradient => Some((self::MACRO, 0)),
                SyntaxKind::AtTr => Some((self::MACRO, 0)),
                SyntaxKind::ConditionalExpression => Some((self::KEYWORD, 0)),
                SyntaxKind::ObjectMember => Some((self::PROPERTY, 1 << self::DECLARATION)),
                SyntaxKind::States => Some((self::KEYWORD, 0)),
                SyntaxKind::State => Some((self::KEYWORD, 0)),
                SyntaxKind::Transitions => Some((self::KEYWORD, 0)),
                SyntaxKind::Transition => Some((self::KEYWORD, 0)),
                SyntaxKind::ExportsList => Some((self::KEYWORD, 0)),
                SyntaxKind::ExportSpecifier => Some((self::KEYWORD, 0)),
                SyntaxKind::ExportIdentifier => {
                    Some((
                        self::TYPE,
                        if token.parent().parent().is_some_and(|p| {
                            p.children().any(|n| n.kind() == SyntaxKind::ExportName)
                        }) {
                            0
                        } else {
                            1 << self::DECLARATION
                        },
                    ))
                }
                SyntaxKind::ExportName => Some((self::TYPE, 1 << self::DECLARATION)),
                SyntaxKind::ImportSpecifier => Some((self::KEYWORD, 0)),
                SyntaxKind::ImportIdentifier => Some((self::KEYWORD, 0)),
                SyntaxKind::ExternalName => {
                    Some((
                        self::TYPE,
                        if token.parent().parent().is_some_and(|p| {
                            p.children().any(|n| n.kind() == SyntaxKind::InternalName)
                        }) {
                            0
                        } else {
                            1 << self::DECLARATION
                        },
                    ))
                }
                SyntaxKind::InternalName => Some((self::TYPE, 1 << self::DECLARATION)),
                SyntaxKind::ObjectTypeMember => Some((self::PROPERTY, 1 << self::DEFINITION)),
                SyntaxKind::StructDeclaration => Some((self::KEYWORD, 0)),
                SyntaxKind::EnumDeclaration => Some((self::KEYWORD, 0)),
                SyntaxKind::PropertyChangedCallback => Some((self::KEYWORD, 0)),
                _ => None,
            },
            SyntaxKind::PlusEqual
            | SyntaxKind::MinusEqual
            | SyntaxKind::StarEqual
            | SyntaxKind::DivEqual
            | SyntaxKind::LessEqual
            | SyntaxKind::GreaterEqual
            | SyntaxKind::EqualEqual
            | SyntaxKind::NotEqual
            | SyntaxKind::OrOr
            | SyntaxKind::AndAnd => Some((self::OPERATOR, 0)),
            SyntaxKind::LAngle | SyntaxKind::RAngle => (token.parent().kind()
                == SyntaxKind::PropertyDeclaration)
                .then_some((self::OPERATOR, 0)),
            SyntaxKind::Plus
            | SyntaxKind::Minus
            | SyntaxKind::Star
            | SyntaxKind::Div
            | SyntaxKind::Equal => Some((self::OPERATOR, 0)),
            SyntaxKind::Question => Some((self::OPERATOR, 0)),
            SyntaxKind::At => Some((self::MACRO, 0)),
            _ => None,
        };
        let len = |txt: &str| -> u32 {
            match document_cache.format {
                crate::common::ByteFormat::Utf8 => txt.len() as u32,
                crate::common::ByteFormat::Utf16 => txt.encode_utf16().count() as u32,
            }
        };
        if let Some((token_type, token_modifiers_bitset)) = t_m {
            data.push(SemanticToken {
                delta_line,
                delta_start,
                length: len(token.text()),
                token_type,
                token_modifiers_bitset,
            });
            delta_line = 0;
            delta_start = 0;
        }
        let text = token.text();
        let l = text.bytes().filter(|x| *x == b'\n').count();
        if l == 0 {
            delta_start += len(text);
        } else {
            delta_line += l as u32;
            delta_start = len(&text[(text.rfind('\n').unwrap() + 1)..]);
        }
        token = match token.next_token() {
            None => break,
            Some(token) => token,
        }
    }
    Some(SemanticTokensResult::Tokens(SemanticTokens { result_id: None, data }))
}
