// 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 std::io::{BufWriter, Write};
use std::path::Path;

/// Returns a list of all the `.slint` files in the `tests/cases` subfolders.
pub fn collect_test_cases() -> std::io::Result<Vec<test_driver_lib::TestCase>> {
    let mut results = vec![];

    let case_root_dir: std::path::PathBuf = [env!("CARGO_MANIFEST_DIR"), "cases"].iter().collect();

    println!("cargo:rerun-if-env-changed=SLINT_TEST_FILTER");
    let filter = std::env::var("SLINT_TEST_FILTER").ok();

    for entry in walkdir::WalkDir::new(case_root_dir.clone()).follow_links(true) {
        let entry = entry?;
        let absolute_path = entry.into_path();
        if absolute_path.is_dir() {
            println!("cargo:rerun-if-changed={}", absolute_path.display());
            continue;
        }
        let relative_path =
            std::path::PathBuf::from(absolute_path.strip_prefix(&case_root_dir).unwrap());
        if let Some(filter) = &filter {
            if !relative_path.to_str().unwrap().contains(filter) {
                continue;
            }
        }
        if let Some(ext) = absolute_path.extension() {
            if ext == "60" || ext == "slint" {
                results.push(test_driver_lib::TestCase {
                    absolute_path,
                    relative_path,
                    requested_style: None,
                });
            }
        }
    }
    Ok(results)
}

fn main() -> std::io::Result<()> {
    let default_font_path: std::path::PathBuf =
        [env!("CARGO_MANIFEST_DIR"), "..", "..", "demos", "printerdemo", "ui", "fonts"]
            .iter()
            .collect();

    std::env::set_var("SLINT_DEFAULT_FONT", default_font_path.clone());
    println!("cargo:rustc-env=SLINT_DEFAULT_FONT={}", default_font_path.display());

    let mut generated_file = BufWriter::new(std::fs::File::create(
        Path::new(&std::env::var_os("OUT_DIR").unwrap()).join("generated.rs"),
    )?);

    let references_root_dir: std::path::PathBuf =
        [env!("CARGO_MANIFEST_DIR"), "references"].iter().collect();

    let font_cache = i_slint_compiler::FontCache::default();

    for (i, testcase) in
        test_driver_lib::collect_test_cases("screenshots/cases")?.into_iter().enumerate()
    {
        let mut reference_path = references_root_dir
            .join(testcase.relative_path.clone())
            .with_extension("png")
            .to_str()
            .unwrap()
            .escape_default()
            .to_string();

        reference_path = format!("\"{reference_path}\"");

        println!("cargo:rerun-if-changed={}", testcase.absolute_path.display());
        let mut module_name = testcase.identifier();
        if module_name.starts_with(|c: char| !c.is_ascii_alphabetic()) {
            module_name.insert(0, '_');
        }
        writeln!(generated_file, "#[path=\"{module_name}.rs\"] mod r#{module_name};")?;
        let source = std::fs::read_to_string(&testcase.absolute_path)?;

        let needle = "SLINT_SCALE_FACTOR=";
        let scale_factor = source.find(needle).map(|p| {
            let source = &source[p + needle.len()..];
            let scale_factor: f32 = source
                .find(char::is_whitespace)
                .and_then(|end| source[..end].parse().ok())
                .unwrap_or_else(|| {
                    panic!("Cannot parse {needle} for {}", testcase.relative_path.display())
                });
            scale_factor
        });

        let needle = "BASE_THRESHOLD=";
        let base_threshold = source.find(needle).map_or(0., |p| {
            source[p + needle.len()..]
                .find(char::is_whitespace)
                .and_then(|end| source[p + needle.len()..][..end].parse().ok())
                .unwrap_or_else(|| {
                    panic!("Cannot parse {needle} for {}", testcase.relative_path.display())
                })
        });
        let needle = "ROTATION_THRESHOLD=";
        let rotation_threshold = source.find(needle).map_or(0., |p| {
            source[p + needle.len()..]
                .find(char::is_whitespace)
                .and_then(|end| source[p + needle.len()..][..end].parse().ok())
                .unwrap_or_else(|| {
                    panic!("Cannot parse {needle} for {}", testcase.relative_path.display())
                })
        });
        let skip_clipping = source.contains("SKIP_CLIPPING");

        let needle = "SIZE=";
        let (size_w, size_h) = source.find(needle).map_or((64, 64), |p| {
            source[p + needle.len()..]
                .find(char::is_whitespace)
                .and_then(|end| source[p + needle.len()..][..end].split_once('x'))
                .and_then(|(w, h)| Some((w.parse().ok()?, h.parse().ok()?)))
                .unwrap_or_else(|| {
                    panic!("Cannot parse {needle} for {}", testcase.relative_path.display())
                })
        });

        let mut output = BufWriter::new(std::fs::File::create(
            Path::new(&std::env::var_os("OUT_DIR").unwrap()).join(format!("{module_name}.rs")),
        )?);

        generate_source(
            source.as_str(),
            &mut output,
            testcase,
            scale_factor.unwrap_or(1.),
            &font_cache,
        )
        .unwrap();

        write!(
            output,
            r"
    #[test] fn t_{i}() -> Result<(), Box<dyn std::error::Error>> {{
    use crate::testing;

    let window = testing::init_swr();
    window.set_size(slint::PhysicalSize::new({size_w}, {size_h}));
    let screenshot = {reference_path};
    let options = testing::TestCaseOptions {{ base_threshold: {base_threshold}f32, rotation_threshold: {rotation_threshold}f32, skip_clipping: {skip_clipping} }};

    let instance = TestCase::new().unwrap();
    instance.show().unwrap();

    testing::assert_with_render(screenshot, window.clone(), &options);

    testing::assert_with_render_by_line(screenshot, window.clone(), &options);

    Ok(())
    }}",
        )?;

        output.flush()?;
    }

    generated_file.flush()?;

    //Make sure to use a consistent style
    println!("cargo:rustc-env=SLINT_STYLE=fluent");
    println!("cargo:rustc-env=SLINT_ENABLE_EXPERIMENTAL_FEATURES=1");

    Ok(())
}

fn generate_source(
    source: &str,
    output: &mut impl Write,
    testcase: test_driver_lib::TestCase,
    scale_factor: f32,
    font_cache: &i_slint_compiler::FontCache,
) -> Result<(), std::io::Error> {
    use i_slint_compiler::{diagnostics::BuildDiagnostics, *};

    let include_paths = test_driver_lib::extract_include_paths(source)
        .map(std::path::PathBuf::from)
        .collect::<Vec<_>>();

    let mut diag = BuildDiagnostics::default();
    let syntax_node = parser::parse(source.to_owned(), Some(&testcase.absolute_path), &mut diag);
    let mut compiler_config = CompilerConfiguration::new(generator::OutputFormat::Rust);
    compiler_config.include_paths = include_paths;
    compiler_config.embed_resources = EmbedResourcesKind::EmbedTextures;
    compiler_config.enable_experimental = true;
    compiler_config.style = Some("fluent".to_string());
    compiler_config.const_scale_factor = scale_factor.into();
    compiler_config.font_cache = font_cache.clone();
    let (root_component, diag, loader) =
        spin_on::spin_on(compile_syntax_node(syntax_node, diag, compiler_config));

    if diag.has_errors() {
        diag.print_warnings_and_exit_on_error();
        return Err(std::io::Error::new(
            std::io::ErrorKind::Other,
            format!("build error in {:?}", testcase.absolute_path),
        ));
    } else {
        diag.print();
    }

    generator::generate(
        generator::OutputFormat::Rust,
        output,
        &root_component,
        &loader.compiler_config,
    )?;
    Ok(())
}