use benchmarks::bench_utils::random_rust_file;
use gpui::{
    AppContext as _, BenchAppContext, Context, Entity, IntoElement, Render, SharedString, Window,
};
use language::LanguageRegistry;
use markdown::{
    CodeBlockRenderer, CopyButtonVisibility, Markdown, MarkdownElement, MarkdownFont,
    MarkdownOptions, MarkdownStyle, WrapButtonVisibility,
};
use rand::{Rng as _, SeedableRng as _, rngs::StdRng};
use settings::SettingsStore;
use std::sync::Arc;
use ui::prelude::*;

const SEED: u64 = 1;

#[gpui::bench(
    inputs = markdown_sizes(),
    group = "Markdown render",
    input_name = "min_bytes",
    sample_size = 10
)]
fn markdown_render(target_size: &usize, cx: &mut BenchAppContext) {
    init_context(cx);

    let source = SharedString::from(generate_markdown(SEED, *target_size));
    let language_registry = markdown_language_registry(cx);

    let mut window = cx.add_empty_window();
    let view = window.update(|window, cx| {
        let markdown = cx.new({
            let source = source.clone();
            let language_registry = language_registry.clone();
            move |cx| build_markdown(source, language_registry, cx)
        });
        window.replace_root(cx, |_window, _cx| MarkdownBenchView { markdown })
    });

    cx.bench_renderer(view, |_, _, cx| cx.notify());
}

struct MarkdownBenchView {
    markdown: Entity<Markdown>,
}

impl Render for MarkdownBenchView {
    fn render(&mut self, window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
        let style = MarkdownStyle::themed(MarkdownFont::Preview, window, cx);

        div().w_full().h_full().child(
            MarkdownElement::new(self.markdown.clone(), style).code_block_renderer(
                CodeBlockRenderer::Default {
                    copy_button_visibility: CopyButtonVisibility::VisibleOnHover,
                    wrap_button_visibility: WrapButtonVisibility::VisibleOnHover,
                    border: false,
                },
            ),
        )
    }
}

fn build_markdown(
    source: SharedString,
    language_registry: Arc<LanguageRegistry>,
    cx: &mut Context<Markdown>,
) -> Markdown {
    Markdown::new_with_options(
        source,
        Some(language_registry),
        None,
        MarkdownOptions {
            // Mermaid and embedded resources need their own focused benchmarks.
            render_metadata_blocks: true,
            ..Default::default()
        },
        cx,
    )
}

fn generate_markdown(seed: u64, target_size: usize) -> String {
    let mut rng = StdRng::seed_from_u64(seed);
    let mut markdown = String::with_capacity(target_size);

    markdown.push_str("---\n");
    markdown.push_str("title: Markdown renderer benchmark\n");
    markdown.push_str("author: Zed benchmark\n");
    markdown.push_str("---\n\n");

    while markdown.len() < target_size {
        push_mixed_block(&mut markdown, &mut rng);
    }

    markdown
}

fn push_mixed_block(markdown: &mut String, rng: &mut StdRng) {
    match rng.random_range(0..10) {
        0 => push_heading(markdown, rng),
        1 | 2 => push_paragraph(markdown, rng),
        3 => push_list(markdown, rng),
        4 => push_task_list(markdown, rng),
        5 => push_table(markdown, rng),
        6 | 7 => push_code_block(markdown, rng),
        8 => push_block_quote(markdown, rng),
        _ => push_rule(markdown),
    }
}

fn push_heading(markdown: &mut String, rng: &mut StdRng) {
    let level = rng.random_range(1..=4);
    markdown.push_str(&"#".repeat(level));
    markdown.push(' ');
    let word_count = rng.random_range(3..8);
    push_words(markdown, rng, word_count);
    markdown.push_str("\n\n");
}

fn push_paragraph(markdown: &mut String, rng: &mut StdRng) {
    let sentence_count = rng.random_range(2..7);
    for sentence_index in 0..sentence_count {
        if sentence_index > 0 {
            markdown.push(' ');
        }
        push_sentence(markdown, rng);
    }
    markdown.push_str("\n\n");
}

fn push_sentence(markdown: &mut String, rng: &mut StdRng) {
    let word_count = rng.random_range(8..24);
    for word_index in 0..word_count {
        if word_index > 0 {
            markdown.push(' ');
        }

        match rng.random_range(0..18) {
            0 => {
                markdown.push_str("**");
                markdown.push_str(random_word(rng));
                markdown.push_str("**");
            }
            1 => {
                markdown.push('*');
                markdown.push_str(random_word(rng));
                markdown.push('*');
            }
            2 => {
                markdown.push('`');
                markdown.push_str(random_identifier(rng));
                markdown.push('`');
            }
            3 => {
                markdown.push('[');
                markdown.push_str(random_word(rng));
                markdown.push_str("](https://example.com/");
                markdown.push_str(random_identifier(rng));
                markdown.push(')');
            }
            4 => {
                markdown.push_str("https://zed.dev/");
                markdown.push_str(random_identifier(rng));
            }
            _ => markdown.push_str(random_word(rng)),
        }
    }
    markdown.push('.');
}

fn push_list(markdown: &mut String, rng: &mut StdRng) {
    let item_count = rng.random_range(3..9);
    let ordered = rng.random();
    for item_index in 0..item_count {
        if ordered {
            markdown.push_str(&(item_index + 1).to_string());
            markdown.push_str(". ");
        } else {
            markdown.push_str("- ");
        }
        let word_count = rng.random_range(5..14);
        push_words(markdown, rng, word_count);
        markdown.push('\n');
    }
    markdown.push('\n');
}

fn push_task_list(markdown: &mut String, rng: &mut StdRng) {
    let item_count = rng.random_range(3..8);
    for _ in 0..item_count {
        if rng.random() {
            markdown.push_str("- [x] ");
        } else {
            markdown.push_str("- [ ] ");
        }
        let word_count = rng.random_range(4..12);
        push_words(markdown, rng, word_count);
        markdown.push('\n');
    }
    markdown.push('\n');
}

fn push_table(markdown: &mut String, rng: &mut StdRng) {
    let column_count = rng.random_range(3..7);
    let row_count = rng.random_range(3..9);

    for column_index in 0..column_count {
        if column_index == 0 {
            markdown.push('|');
        }
        markdown.push(' ');
        markdown.push_str(random_word(rng));
        markdown.push(' ');
        markdown.push('|');
    }
    markdown.push('\n');

    for column_index in 0..column_count {
        if column_index == 0 {
            markdown.push('|');
        }
        markdown.push_str(" --- |");
    }
    markdown.push('\n');

    for _ in 0..row_count {
        for column_index in 0..column_count {
            if column_index == 0 {
                markdown.push('|');
            }
            markdown.push(' ');
            let word_count = rng.random_range(2..6);
            push_words(markdown, rng, word_count);
            markdown.push(' ');
            markdown.push('|');
        }
        markdown.push('\n');
    }
    markdown.push('\n');
}

fn push_code_block(markdown: &mut String, rng: &mut StdRng) {
    let line_count = rng.random_range(24..80);
    let rust = random_rust_file(rng, line_count);
    markdown.push_str("```rust\n");
    markdown.push_str(&rust.join("\n"));
    markdown.push_str("\n```\n\n");
}

fn push_block_quote(markdown: &mut String, rng: &mut StdRng) {
    let line_count = rng.random_range(2..6);
    for _ in 0..line_count {
        markdown.push_str("> ");
        push_sentence(markdown, rng);
        markdown.push('\n');
    }
    markdown.push('\n');
}

fn push_rule(markdown: &mut String) {
    markdown.push_str("---\n\n");
}

fn push_words(markdown: &mut String, rng: &mut StdRng, word_count: usize) {
    for word_index in 0..word_count {
        if word_index > 0 {
            markdown.push(' ');
        }
        markdown.push_str(random_word(rng));
    }
}

fn random_word(rng: &mut StdRng) -> &'static str {
    const WORDS: &[&str] = &[
        "renderer",
        "layout",
        "markdown",
        "paragraph",
        "heading",
        "table",
        "selection",
        "syntax",
        "highlight",
        "window",
        "element",
        "callback",
        "benchmark",
        "profile",
        "latency",
        "throughput",
        "scroll",
        "wrapping",
        "theme",
        "language",
        "fenced",
        "blockquote",
        "inline",
        "content",
    ];
    choose(rng, WORDS)
}

fn random_identifier(rng: &mut StdRng) -> &'static str {
    const IDENTIFIERS: &[&str] = &[
        "markdown_renderer",
        "layout_cache",
        "rendered_text",
        "source_range",
        "bench_input",
        "window_state",
        "code_block",
        "table_row",
        "link_target",
        "scroll_handle",
        "text_style",
        "root_block",
    ];
    choose(rng, IDENTIFIERS)
}

fn choose(rng: &mut StdRng, items: &'static [&'static str]) -> &'static str {
    let index = rng.random_range(0..items.len());
    items.get(index).copied().unwrap_or("markdown")
}

fn markdown_language_registry(cx: &BenchAppContext) -> Arc<LanguageRegistry> {
    let registry = Arc::new(LanguageRegistry::test(cx.background_executor().clone()));
    registry.add(language::rust_lang());
    registry
}

fn init_context(cx: &mut BenchAppContext) {
    cx.update(|cx| {
        let store = SettingsStore::test(cx);
        cx.set_global(store);
        assets::Assets.load_test_fonts(cx);
        theme_settings::init(theme::LoadThemes::JustBase, cx);
    });
}

fn markdown_sizes() -> Vec<usize> {
    let mut sizes = vec![5_000, 10_000, 50_000, 250_000];
    if std::env::var("ZED_BENCH_HUGE").is_ok() {
        sizes.push(1_000_000);
    }
    sizes
}

gpui::bench_group!(benches, markdown_render);
gpui::bench_main!(benches);