use libloading::Library;
use roc_build::link::module_to_dylib;
use roc_collections::all::{MutMap, MutSet};

fn promote_expr_to_module(src: &str) -> String {
    let mut buffer = String::from("app Test provides [ main ] imports []\n\nmain =\n");

    for line in src.lines() {
        // indent the body!
        buffer.push_str("    ");
        buffer.push_str(line);
        buffer.push('\n');
    }

    buffer
}

pub fn helper<'a>(
    arena: &'a bumpalo::Bump,
    src: &str,
    stdlib: roc_builtins::std::StdLib,
    leak: bool,
    context: &'a inkwell::context::Context,
) -> (&'static str, Vec<roc_problem::can::Problem>, Library) {
    use roc_gen::llvm::build::{build_proc, build_proc_header, Scope};
    use std::path::{Path, PathBuf};

    let stdlib_mode = stdlib.mode;
    let filename = PathBuf::from("Test.roc");
    let src_dir = Path::new("fake/test/path");

    let module_src;
    let temp;
    if src.starts_with("app") {
        // this is already a module
        module_src = src;
    } else {
        // this is an expression, promote it to a module
        temp = promote_expr_to_module(src);
        module_src = &temp;
    }

    let exposed_types = MutMap::default();
    let loaded = roc_load::file::load_and_monomorphize_from_str(
        arena,
        filename,
        &module_src,
        stdlib,
        src_dir,
        exposed_types,
    );

    let loaded = loaded.expect("failed to load module");

    use roc_load::file::MonomorphizedModule;
    let MonomorphizedModule {
        module_id: home,
        can_problems,
        type_problems,
        mono_problems,
        mut procedures,
        interns,
        exposed_to_host,
        ..
    } = loaded;

    debug_assert_eq!(exposed_to_host.len(), 1);
    let main_fn_symbol = exposed_to_host.keys().copied().nth(0).unwrap();

    let (_, main_fn_layout) = procedures
        .keys()
        .find(|(s, _)| *s == main_fn_symbol)
        .unwrap()
        .clone();

    let target = target_lexicon::Triple::host();
    let ptr_bytes = target.pointer_width().unwrap().bytes() as u32;

    // don't panic based on the errors here, so we can test that RuntimeError generates the correct code
    let errors = can_problems
        .into_iter()
        .filter(|problem| {
            use roc_problem::can::Problem::*;

            // Ignore "unused" problems
            match problem {
                UnusedDef(_, _) | UnusedArgument(_, _, _) | UnusedImport(_, _) => false,
                _ => true,
            }
        })
        .collect::<Vec<roc_problem::can::Problem>>();

    use roc_reporting::report::{
        can_problem, mono_problem, type_problem, RocDocAllocator, DEFAULT_PALETTE,
    };

    let error_count = errors.len() + type_problems.len() + mono_problems.len();
    let fatal_error_count = type_problems.len() + mono_problems.len();

    if error_count > 0 {
        // There were problems; report them and return.
        let src_lines: Vec<&str> = module_src.split('\n').collect();

        // Used for reporting where an error came from.
        //
        // TODO: maybe Reporting should have this be an Option?
        let path = PathBuf::new();

        // Report problems
        let palette = DEFAULT_PALETTE;

        // Report parsing and canonicalization problems
        let alloc = RocDocAllocator::new(&src_lines, home, &interns);

        let mut lines = Vec::with_capacity(error_count);

        let can_problems = errors.clone();
        for problem in can_problems.into_iter() {
            let report = can_problem(&alloc, path.clone(), problem);
            let mut buf = String::new();

            report.render_color_terminal(&mut buf, &alloc, &palette);

            lines.push(buf);
        }

        for problem in type_problems.into_iter() {
            let report = type_problem(&alloc, path.clone(), problem);
            let mut buf = String::new();

            report.render_color_terminal(&mut buf, &alloc, &palette);

            lines.push(buf);
        }

        for problem in mono_problems.into_iter() {
            let report = mono_problem(&alloc, path.clone(), problem);
            let mut buf = String::new();

            report.render_color_terminal(&mut buf, &alloc, &palette);

            lines.push(buf);
        }

        println!("{}", (&lines).join("\n"));

        // we want to continue onward only for canonical problems at the moment,
        // to check that they codegen into runtime exceptions
        if fatal_error_count > 0 {
            assert_eq!(0, 1, "problems occured");
        }
    }

    let module = roc_gen::llvm::build::module_from_builtins(context, "app");
    let builder = context.create_builder();
    let opt_level = if cfg!(debug_assertions) {
        roc_gen::llvm::build::OptLevel::Normal
    } else {
        roc_gen::llvm::build::OptLevel::Optimize
    };

    let module = arena.alloc(module);
    let (module_pass, function_pass) =
        roc_gen::llvm::build::construct_optimization_passes(module, opt_level);

    // Compile and add all the Procs before adding main
    let env = roc_gen::llvm::build::Env {
        arena: &arena,
        builder: &builder,
        context,
        interns,
        module,
        ptr_bytes,
        leak,
        // important! we don't want any procedures to get the C calling convention
        exposed_to_host: MutSet::default(),
    };

    let mut layout_ids = roc_gen::layout_id::LayoutIds::default();
    let mut headers = Vec::with_capacity(procedures.len());

    // Add all the Proc headers to the module.
    // We have to do this in a separate pass first,
    // because their bodies may reference each other.
    let mut scope = Scope::default();
    for ((symbol, layout), proc) in procedures.drain() {
        let fn_val = build_proc_header(&env, &mut layout_ids, symbol, &layout, &proc);

        if proc.args.is_empty() {
            // this is a 0-argument thunk, i.e. a top-level constant definition
            // it must be in-scope everywhere in the module!
            scope.insert_top_level_thunk(symbol, layout, fn_val);
        }

        headers.push((proc, fn_val));
    }

    // Build each proc using its header info.
    for (proc, fn_val) in headers {
        let mut current_scope = scope.clone();

        // only have top-level thunks for this proc's module in scope
        // this retain is not needed for correctness, but will cause less confusion when debugging
        let home = proc.name.module_id();
        current_scope.retain_top_level_thunks_for_module(home);

        build_proc(&env, &mut layout_ids, scope.clone(), proc, fn_val);

        if fn_val.verify(true) {
            function_pass.run_on(&fn_val);
        } else {
            use roc_builtins::std::Mode;

            let mode = match stdlib_mode {
                Mode::Uniqueness => "OPTIMIZED",
                Mode::Standard => "NON-OPTIMIZED",
            };

            eprintln!(
                "\n\nFunction {:?} failed LLVM verification in {} build. Its content was:\n",
                fn_val.get_name().to_str().unwrap(),
                mode,
            );

            fn_val.print_to_stderr();
            // module.print_to_stderr();

            panic!(
                "The preceding code was from {:?}, which failed LLVM verification in {} build.",
                fn_val.get_name().to_str().unwrap(),
                mode,
            );
        }
    }
    let (main_fn_name, main_fn) = roc_gen::llvm::build::promote_to_main_function(
        &env,
        &mut layout_ids,
        main_fn_symbol,
        &main_fn_layout,
    );

    // Uncomment this to see the module's un-optimized LLVM instruction output:
    // env.module.print_to_stderr();

    if main_fn.verify(true) {
        function_pass.run_on(&main_fn);
    } else {
        panic!("Main function {} failed LLVM verification in NON-OPTIMIZED build. Uncomment things nearby to see more details.", main_fn_name);
    }

    module_pass.run_on(env.module);

    // Verify the module
    if let Err(errors) = env.module.verify() {
        panic!("Errors defining module: {:?}", errors);
    }

    // Uncomment this to see the module's optimized LLVM instruction output:
    // env.module.print_to_stderr();

    let lib = module_to_dylib(&env.module, &target, opt_level)
        .expect("Error loading compiled dylib for test");

    (main_fn_name, errors, lib)
}

// TODO this is almost all code duplication with assert_llvm_evals_to
// the only difference is that this calls uniq_expr instead of can_expr.
// Should extract the common logic into test helpers.
#[macro_export]
macro_rules! assert_opt_evals_to {
    ($src:expr, $expected:expr, $ty:ty, $transform:expr, $leak:expr) => {
        use bumpalo::Bump;
        use inkwell::context::Context;
        use roc_gen::run_jit_function;

        let arena = Bump::new();

        let context = Context::create();

        let stdlib = roc_builtins::unique::uniq_stdlib();

        let (main_fn_name, errors, lib) =
            $crate::helpers::eval::helper(&arena, $src, stdlib, $leak, &context);

        let transform = |success| {
            let expected = $expected;
            let given = $transform(success);
            assert_eq!(&given, &expected);
        };
        run_jit_function!(lib, main_fn_name, $ty, transform, errors)
    };

    ($src:expr, $expected:expr, $ty:ty, $transform:expr) => {
        assert_opt_evals_to!($src, $expected, $ty, $transform, true)
    };
}

#[macro_export]
macro_rules! assert_llvm_evals_to {
    ($src:expr, $expected:expr, $ty:ty, $transform:expr, $leak:expr) => {
        use bumpalo::Bump;
        use inkwell::context::Context;
        use roc_gen::run_jit_function;

        let arena = Bump::new();

        let context = Context::create();
        let stdlib = roc_builtins::std::standard_stdlib();

        let (main_fn_name, errors, lib) =
            $crate::helpers::eval::helper(&arena, $src, stdlib, $leak, &context);

        let transform = |success| {
            let expected = $expected;
            let given = $transform(success);
            assert_eq!(&given, &expected);
        };
        run_jit_function!(lib, main_fn_name, $ty, transform, errors)
    };

    ($src:expr, $expected:expr, $ty:ty, $transform:expr) => {
        assert_llvm_evals_to!($src, $expected, $ty, $transform, true);
    };
}

#[macro_export]
macro_rules! assert_evals_to {
    ($src:expr, $expected:expr, $ty:ty) => {{
        assert_evals_to!($src, $expected, $ty, (|val| val));
    }};
    ($src:expr, $expected:expr, $ty:ty, $transform:expr) => {
        // Same as above, except with an additional transformation argument.
        {
            assert_evals_to!($src, $expected, $ty, $transform, true);
        }
    };
    ($src:expr, $expected:expr, $ty:ty, $transform:expr, $leak:expr) => {
        // Run un-optimized tests, and then optimized tests, in separate scopes.
        // These each rebuild everything from scratch, starting with
        // parsing the source, so that there's no chance their passing
        // or failing depends on leftover state from the previous one.
        {
            assert_llvm_evals_to!($src, $expected, $ty, $transform, $leak);
        }
        {
            assert_opt_evals_to!($src, $expected, $ty, $transform, $leak);
        }
    };
}