//! Tests for the pure helpers that the LSP backend uses to translate
//! between `nuwiki-core` ASTs and the LSP wire format. The async
//! request-handling loop is exercised at integration time in Phase 8+
//! (navigation), so this file stays focused on conversion correctness.

use nuwiki_core::ast::{
    inline::InlineNode, BlockNode, BlockquoteNode, DocumentNode, ErrorNode, ParagraphNode,
    Position, Span, TextNode,
};
use nuwiki_core::syntax::vimwiki::VimwikiSyntax;
use nuwiki_core::syntax::SyntaxPlugin;
use nuwiki_lsp::{ast_diagnostics, headings_to_symbols, to_lsp_position, to_lsp_range};
use tower_lsp::lsp_types::{DiagnosticSeverity, DocumentSymbolResponse, SymbolKind};

// ===== Position / Range conversion =====

#[test]
fn position_passthrough_in_utf8_mode() {
    let pos = Position {
        line: 3,
        column: 7,
        offset: 0,
    };
    let lsp = to_lsp_position(&pos, "ignored", true);
    assert_eq!(lsp.line, 3);
    assert_eq!(lsp.character, 7);
}

#[test]
fn position_translates_to_utf16_for_multibyte_chars() {
    // "héllo" in UTF-8: h(1) é(2 bytes) l(1) l(1) o(1) — total 6 bytes.
    // In UTF-16 each char is one code unit (BMP), so byte col 3 ("after é")
    // maps to UTF-16 char col 2.
    let line = "héllo\nworld\n";
    let pos = Position {
        line: 0,
        column: 3,
        offset: 3,
    };
    let lsp = to_lsp_position(&pos, line, false);
    assert_eq!(lsp.line, 0);
    assert_eq!(lsp.character, 2);
}

#[test]
fn position_handles_astral_plane_in_utf16() {
    // 🦀 is U+1F980, two UTF-16 code units (surrogate pair), four UTF-8 bytes.
    let text = "🦀x\n";
    // After the crab + x, byte col is 5, UTF-16 col is 3 (2 surrogates + 1 BMP).
    let pos = Position {
        line: 0,
        column: 5,
        offset: 5,
    };
    let lsp = to_lsp_position(&pos, text, false);
    assert_eq!(lsp.character, 3);
}

#[test]
fn range_passthrough_in_utf8_mode() {
    let span = Span::new(
        Position {
            line: 0,
            column: 0,
            offset: 0,
        },
        Position {
            line: 0,
            column: 5,
            offset: 5,
        },
    );
    let r = to_lsp_range(&span, "hello\n", true);
    assert_eq!(r.start.line, 0);
    assert_eq!(r.start.character, 0);
    assert_eq!(r.end.character, 5);
}

// ===== Diagnostics =====

#[test]
fn ast_diagnostics_yields_one_per_error_node() {
    let span_a = Span::new(
        Position {
            line: 0,
            column: 0,
            offset: 0,
        },
        Position {
            line: 0,
            column: 4,
            offset: 4,
        },
    );
    let span_b = Span::new(
        Position {
            line: 2,
            column: 0,
            offset: 10,
        },
        Position {
            line: 2,
            column: 3,
            offset: 13,
        },
    );
    let doc = DocumentNode {
        span: Span::default(),
        metadata: Default::default(),
        children: vec![
            BlockNode::Error(ErrorNode {
                span: span_a,
                raw: "first".into(),
                message: "first parse failure".into(),
            }),
            BlockNode::Paragraph(ParagraphNode {
                span: Span::default(),
                children: vec![InlineNode::Text(TextNode {
                    span: Span::default(),
                    content: "ok".into(),
                })],
            }),
            BlockNode::Error(ErrorNode {
                span: span_b,
                raw: "second".into(),
                message: "second parse failure".into(),
            }),
        ],
    };

    let diags = ast_diagnostics(&doc, "ignored", true);
    assert_eq!(diags.len(), 2);
    assert_eq!(diags[0].message, "first parse failure");
    assert_eq!(diags[0].severity, Some(DiagnosticSeverity::ERROR));
    assert_eq!(diags[0].source.as_deref(), Some("nuwiki"));
    assert_eq!(diags[0].range.start.line, 0);
    assert_eq!(diags[1].range.start.line, 2);
}

#[test]
fn ast_diagnostics_descends_into_blockquotes() {
    let span = Span::new(
        Position {
            line: 1,
            column: 2,
            offset: 0,
        },
        Position {
            line: 1,
            column: 6,
            offset: 4,
        },
    );
    let inner_error = BlockNode::Error(ErrorNode {
        span,
        raw: "x".into(),
        message: "nested".into(),
    });
    let bq = BlockNode::Blockquote(BlockquoteNode {
        span: Span::default(),
        children: vec![inner_error],
    });
    let doc = DocumentNode {
        span: Span::default(),
        metadata: Default::default(),
        children: vec![bq],
    };

    let diags = ast_diagnostics(&doc, "", true);
    assert_eq!(diags.len(), 1);
    assert_eq!(diags[0].message, "nested");
}

// ===== Document symbols =====

fn parse(src: &str) -> DocumentNode {
    VimwikiSyntax::new().parse(src)
}

#[test]
fn flat_outline_when_all_headings_same_level() {
    let doc = parse("= A =\n= B =\n= C =\n");
    let syms = headings_to_symbols(&doc, "", true);
    assert_eq!(syms.len(), 3);
    let names: Vec<&str> = syms.iter().map(|s| s.name.as_str()).collect();
    assert_eq!(names, vec!["A", "B", "C"]);
    for s in &syms {
        assert!(s.children.is_none() || s.children.as_ref().unwrap().is_empty());
        assert_eq!(s.kind, SymbolKind::STRING);
    }
}

#[test]
fn nested_outline_follows_heading_levels() {
    let src = "\
= Top =
== Sub A ==
=== Deeper ===
== Sub B ==
= Other =
";
    let doc = parse(src);
    let syms = headings_to_symbols(&doc, "", true);
    assert_eq!(syms.len(), 2);

    // Top contains Sub A and Sub B; Sub A contains Deeper.
    let top = &syms[0];
    assert_eq!(top.name, "Top");
    let top_kids = top.children.as_ref().expect("Top should have children");
    assert_eq!(top_kids.len(), 2);
    assert_eq!(top_kids[0].name, "Sub A");
    assert_eq!(top_kids[1].name, "Sub B");

    let sub_a_kids = top_kids[0]
        .children
        .as_ref()
        .expect("Sub A should have children");
    assert_eq!(sub_a_kids.len(), 1);
    assert_eq!(sub_a_kids[0].name, "Deeper");

    assert_eq!(syms[1].name, "Other");
}

#[test]
fn heading_title_strips_inline_markers() {
    let doc = parse("= Hello *world* and `code` =\n");
    let syms = headings_to_symbols(&doc, "", true);
    assert_eq!(syms.len(), 1);
    assert_eq!(syms[0].name, "Hello world and code");
}

#[test]
fn empty_heading_falls_back_to_placeholder_name() {
    let doc = parse("=  =\n");
    let syms = headings_to_symbols(&doc, "", true);
    if let Some(s) = syms.first() {
        assert!(!s.name.is_empty());
    }
}

// ===== End-to-end through the registry =====

#[test]
fn outline_symbols_match_registry_dispatch() {
    let src = "= A =\n== B ==\n";
    let plugin = VimwikiSyntax::new();
    let doc = plugin.parse(src);
    let syms = headings_to_symbols(&doc, src, true);
    assert_eq!(syms.len(), 1);
    assert_eq!(syms[0].name, "A");
    let kids = syms[0].children.as_ref().unwrap();
    assert_eq!(kids[0].name, "B");
    // Sanity: symbols can be wrapped in DocumentSymbolResponse::Nested.
    let _resp = DocumentSymbolResponse::Nested(syms);
}