use crate::exec::{fixtures, runtime};
use crate::reporting::{CompilerError, InterpreterError, Problem, TypeError};
use deno_core::{Extension, OpState};
use elm_project_utils::{setup_generator_project, ElmResult};
use os_pipe::dup_stderr;
use sqlx::sqlite::SqlitePool;
use std::cell::RefCell;
use std::convert::TryFrom;
use std::fs;
use std::io::{self, Read, Write};
use std::path::PathBuf;
use std::process::{Command, Stdio};
use std::sync::Arc;
use tokio;
use tracing::info_span;

pub(crate) fn run(
    debug: bool,
    verbosity: u64,
    sqlite_path: Option<PathBuf>,
    elm_project_dir: PathBuf,
    source_checksum: u64,
    entrypoint: elmi::Global,
    input_type: Option<InputType>,
    output_type: OutputType,
    input_source: Option<PathBuf>,
    output: Option<PathBuf>,
) -> Result<(), Problem> {
    // step 6 create our private project
    let packages = ["ThinkAlexandria/elm-html-in-elm", "elm/json", "elm/bytes"];
    // I added a couple of random bytes to the directory name to reduce the risk of
    // collisions with other programs that also use elm-stuff for their scratch space
    let our_temp_dir = elm_project_dir.join("elm-stuff").join("starmelon-5d9ecc");
    let generator_dir =
        setup_generator_project(verbosity, elm_project_dir.clone(), our_temp_dir, &packages)?;

    // step 7 create an Elm fixture file to run our function
    let span = info_span!("create Elm fixture files");
    let timing_guard = span.enter();
    let (gen_module_name, source) = fixtures::scripting::generate(
        source_checksum,
        entrypoint.0.module.clone(),
        entrypoint.1.clone(),
        input_type,
        output_type,
    );

    let mut source_filename = generator_dir.join("src").join(&gen_module_name);
    source_filename.set_extension("elm");

    let span = info_span!("file writes");
    let file_write_timing_guard = span.enter();
    fs::File::create(&source_filename)
        .map_err(|io_err| CompilerError::WriteOutputFailed(io_err, source_filename.clone()))?
        .write_all(source.as_bytes())
        .map_err(|io_err| CompilerError::WriteOutputFailed(io_err, source_filename.clone()))?;
    drop(file_write_timing_guard);
    drop(timing_guard);

    // step 8 compile the fixture
    let mut intermediate_file = generator_dir.join("obj").join(&gen_module_name);
    intermediate_file.set_extension("js");

    let mut command = Command::new("elm");

    command
        .arg("make")
        .arg("--output")
        .arg(&intermediate_file)
        .current_dir(&generator_dir)
        .stdin(Stdio::null())
        .stderr(Stdio::piped());
    if verbosity < 1 {
        command.stdout(Stdio::piped());
    } else {
        let pipe = dup_stderr()
            .map_err(|io_err| CompilerError::ReadInputFailed(io_err, "stdout".into()))?;
        command.stdout(pipe);
    }

    if debug {
        command.arg("--debug");
    }
    command.arg(&source_filename);

    let span = info_span!("elm make fixture file");
    let timing_guard = span.enter();
    match command.output() {
        Ok(output) => {
            if !output.status.success() {
                return Err(CompilerError::FailedBuildingFixture.into());
            }
        }
        Err(_) => {
            return Err(CompilerError::FailedBuildingFixture.into());
        }
    }
    drop(timing_guard);

    // Step 9 fixup the compiled script to run in Deno

    let data = fs::read_to_string(&intermediate_file)
        .map_err(|io_err| CompilerError::ReadInputFailed(io_err, intermediate_file.clone()))?;

    // TODO figure out how to replace multiple substrings in a single pass. One neat trick
    // might be to allocate enough space in our starting buffer to write the new code by
    // having a really large replace block. For example if we are replacing a string
    // `"REPLACE_ME" + "abc" * 2000` we would have over 6k bytes to write out the new code. We
    // will have to do some extra book keeping to make sure the buffer space is big enough
    // for the replacement code.
    let span = info_span!("munge fixture javascript");
    let timing_guard = span.enter();
    let final_script = (|| {
        let mut final_script = data
            .replace("'REPLACE_ME_WITH_JSON_STRINGIFY'", "JSON.stringify(x)")
            .replace(
                "$elm$json$Json$Decode$fail('REPLACE_ME_WITH_BYTES_DECODER');",
                r#" _Json_decodePrim(function(value) {
        return (typeof value === 'object' && value instanceof DataView)
            ? $elm$core$Result$Ok(value)
                : _Json_expecting('a DataView', value);
    });"#,
            )
            .replace(";}(this));", ";}(globalThis));");

        if sqlite_path.is_some() {
            final_script = final_script
                .replace(
                    "var $author$project$Astrid$Query$execute = function (query) {\n\treturn $author$project$Astrid$Query$dummyExecute;\n};",
                    include_str!("fixtures/sql-client-integration.js"),
                )
                .replace(
                    "var $author$project$Astrid$Query$fetch = F3(\n\tfunction (sql, parameters, decoder) {\n\t\treturn $author$project$Astrid$Query$Dummy;\n\t});",
                    "var $author$project$Astrid$Query$fetch = _Query_fetchAll;",
                )
                .replace(
                    "var $author$project$Astrid$Query$fetchOne = F3(\n\tfunction (sql, parameters, decoder) {\n\t\treturn $author$project$Astrid$Query$Dummy;\n\t});",
                    "var $author$project$Astrid$Query$fetchOne = _Query_fetchOne;",
                )
                .replace(
                    "var $author$project$Astrid$Query$map3 = F4(\n\tfunction (f, a, b, c) {\n\t\treturn $author$project$Astrid$Query$Dummy;\n\t});",
                    r#"var $author$project$Astrid$Query$map3 = _Query_map3;"#,
                )
                .replace(
                    "var $author$project$Astrid$Query$map2 = F3(\n\tfunction (f, a, b) {\n\t\treturn $author$project$Astrid$Query$Dummy;\n\t});",
                    r#"var $author$project$Astrid$Query$map2 = _Query_map2;"#,
                )
                .replace(
                    "var $author$project$Astrid$Query$map = F2(\n\tfunction (f, a) {\n\t\treturn $author$project$Astrid$Query$Dummy;\n\t});",
                    r#"var $author$project$Astrid$Query$map = _Query_map1;"#,
                )
                .replace(
                    "var $author$project$Astrid$Query$andThen = F2(\n\tfunction (f, q) {\n\t\treturn $author$project$Astrid$Query$Dummy;\n\t});",
                    r#"var $author$project$Astrid$Query$andThen = _Query_andThen;"#,
                );

            // final_script.replace("var $author$project$Astrid$Query$run = ", "JSON.stringify(x)");
            final_script.push_str("\n\n");
            //final_script.push_str(r#"
            //    Deno.core.print(JSON.stringify(
            //        Deno.core.opSync(
            //            'op_starmelon_batch_queries',
            //            [ [true, "select json_object('id', id, 'foo', foo) from foobar", []]
            //            , [false, "select json_object('id', id, 'foo', foo) from foobar", []]
            //            ]
            //        )
            //    ))
            //"#);
        }

        final_script.push_str("\n\n");
        // I think that when I set this script to be the main module, I am skipping the
        // deno/runtime/js/99_main.js script that sets up a bunch of global variables. If I
        // manually add the timer related code below then setTimeout works again.
        // NB. there are 706 lines of setup code that add a bunch of apis to the global window
        // scope. Figure out if I need to include all of them. For example, starmelon does not need
        // to perform http calls right now, but I eventually want to.
        final_script.push_str("const { setTimeout } = globalThis.__bootstrap.timers;\n");
        final_script.push_str(
            "Deno.core.setMacrotaskCallback(globalThis.__bootstrap.timers.handleTimerMacrotask);\n",
        );
        final_script.push_str("globalThis.setTimeout = setTimeout;\n");

        final_script.push_str(&format!("var worker = Elm.{}.init();\n", &gen_module_name));
        // add a shortcut for invoking the function so I don't have to traverse so many object
        // lookups using the rust v8 API.
        match input_type {
            None => {
                final_script.push_str(
                    "globalThis.runOnInput = function() { worker.ports.onInput.send(null) };\n",
                );
            }
            Some(InputType::Value) => {
                final_script
                    .push_str("globalThis.runOnInput = function(data) { worker.ports.onInput.send(JSON.parse(data)) };\n");
            }
            Some(InputType::String) => {
                final_script.push_str(
                    "globalThis.runOnInput = function(data) { worker.ports.onInput.send(data) };",
                );
            }
            Some(InputType::Bytes) => {
                final_script.push_str(
                    r#"
    globalThis.runOnInput = function(data) {
        const dv = new DataView(data.buffer)
        worker.ports.onInput.send(dv)
    };"#,
                );
            }
        }

        match output_type {
            OutputType::Value => {
                final_script.push_str(
                    r#"
                    worker.ports.onOutput.subscribe(function(output){
                        if (output.ctor === "Ok") {
                            const json = JSON.stringify(output.a);
                            Deno.core.opSync('op_starmelon_string_output', output);
                        } else {
                            Deno.core.opSync('op_starmelon_problem', output.a);
                        }
                    });
                "#,
                );
            }
            OutputType::Bytes => {
                final_script.push_str(
                    r#"
                    // Elm will send a DataView
                    worker.ports.onOutput.subscribe(function(output){
                        if (output.ctor === "Ok") {
                            const ui8 = new Uint8Array(output.a.buffer);
                            Deno.core.opSync('op_starmelon_bytes_output', ui8);
                        } else {
                            Deno.core.opSync('op_starmelon_problem', output.a);
                        }
                    });
                "#,
                );
            }
            OutputType::String | OutputType::Html => {
                final_script.push_str(
                    r#"
                    worker.ports.onOutput.subscribe(function(output){
                        if (output.ctor === "Ok") {
                            Deno.core.opSync('op_starmelon_string_output', output.a);
                        } else {
                            Deno.core.opSync('op_starmelon_problem', output.a);
                        }
                    });
                "#,
                );
            }
        }

        final_script
    })();
    drop(timing_guard);

    let mut final_file = generator_dir.join("bin").join(&gen_module_name);
    final_file.set_extension("js");
    let span = info_span!("file writes");
    let timing_guard = span.enter();
    std::fs::write(&final_file, final_script)
        .map_err(|io_err| CompilerError::WriteOutputFailed(io_err, final_file.clone()))?;
    drop(timing_guard);

    // Create a tokio runtime before registering ops so we can block on futures inside sync ops
    let span = info_span!("create tokio runtime");
    let timing_guard = span.enter();
    let sys = tokio::runtime::Builder::new_current_thread()
        // The default number of additional threads for running blocking FnOnce is 512.
        .max_blocking_threads(1)
        .enable_all()
        .build()
        .unwrap();
    drop(timing_guard);

    // step 10 create a v8 isolate. We need to register a different callback depending on
    // the output type (string, or bytes)

    let mailbox: Arc<RefCell<Option<Result<Vec<u8>, String>>>> = Arc::new(RefCell::new(None));
    let mailbox_clone = Arc::clone(&mailbox);

    let mut extensions = vec![Extension::builder()
        .ops(vec![
            op_starmelon_bytes_output::decl(),
            op_starmelon_string_output::decl(),
            op_starmelon_problem::decl(),
        ])
        .state(move |state| {
            state.put(Arc::clone(&mailbox_clone));

            Ok(())
        })
        .build()];

    let span = info_span!("register private api");
    let timing_guard = span.enter();

    // Step 10.B  setup the sqlite database feature
    let sql_background_thread_handle = if let Some(database_url) = sqlite_path {
        // I want to construct the connection in the initial thread so I can tell if the connection
        // failed
        let db_pool = sys
            .block_on(async { SqlitePool::connect(&database_url.to_string_lossy()).await })
            .unwrap();

        if let Ok((extension, thread_handle)) = fixtures::sqlite::init(db_pool) {
            extensions.push(extension);
            Some(thread_handle)
        } else {
            None
        }
    } else {
        None
    };
    drop(timing_guard);

    let span = info_span!("create v8 isolate");
    let timing_guard = span.enter();
    let (worker, main_module) = runtime::setup_worker(extensions, &final_file.to_string_lossy())
        .map_err(|err| InterpreterError::EventLoop(err))?;
    drop(timing_guard);

    // step 11 marshal the input into the v8 isolate. If we are reading from an
    // input file load that, if we are reading from stdin read that.
    let input = match input_type {
        None => None,
        Some(input_type) => {
            let buffer = match input_source {
                None => {
                    // read from stdin when input_source was not present
                    let mut stdin = io::stdin();
                    let mut buffer = Vec::new();
                    stdin.read_to_end(&mut buffer).unwrap();
                    buffer
                }
                Some(path) => {
                    let buffer = std::fs::read(&path)
                        .map_err(|io_err| CompilerError::ReadInputFailed(io_err, path.clone()))?;

                    buffer
                }
            };
            match input_type {
                InputType::String => {
                    let s = String::from_utf8(buffer).map_err(|_| CompilerError::BadInput)?;

                    Some(ValidatedInput::String(s))
                }
                InputType::Bytes => Some(ValidatedInput::Bytes(buffer)),
                InputType::Value => {
                    let _: serde_json::Value =
                        serde_json::from_slice(&buffer).map_err(|_| CompilerError::BadInput)?;

                    let s = String::from_utf8(buffer).map_err(|_| CompilerError::BadInput)?;

                    Some(ValidatedInput::Value(s))
                }
            }
        }
    };

    let foo = move |mut scope: deno_core::v8::HandleScope| -> Result<(), InterpreterError> {
        let scope = &mut scope;
        let ctx = scope.get_current_context();
        let global = ctx.global(scope);
        use deno_core::v8;

        let entrypoint = {
            let x =
                v8::String::new(scope, "runOnInput").ok_or(InterpreterError::AllocationFailed)?;
            v8::Local::new(scope, x).into()
        };
        let v8_value = global
            .get(scope, entrypoint)
            .ok_or(InterpreterError::ReferenceError)?;

        // step 12 invoke the function
        let function = v8::Local::<v8::Function>::try_from(v8_value)?;

        let this = v8::undefined(scope).into();

        let span = info_span!("dispatch v8 call");
        let timing_guard = span.enter();
        match input {
            None => {
                function.call(scope, this, &[]);
            }
            Some(ValidatedInput::String(s)) => {
                let arg1 = {
                    let x = v8::String::new(scope, &s).ok_or(InterpreterError::AllocationFailed)?;
                    v8::Local::new(scope, x).into()
                };

                function.call(scope, this, &[arg1]);
            }
            Some(ValidatedInput::Value(v)) => {
                let arg1 = {
                    let x = v8::String::new(scope, &v).ok_or(InterpreterError::AllocationFailed)?;
                    v8::Local::new(scope, x).into()
                };

                function.call(scope, this, &[arg1]);
            }
            Some(ValidatedInput::Bytes(data)) => {
                let length = data.len();

                let y = data.into_boxed_slice();
                let k = v8::ArrayBuffer::new_backing_store_from_boxed_slice(y).make_shared();
                let x = v8::ArrayBuffer::with_backing_store(scope, &k);

                let arg1 = v8::Local::new(scope, x).into();

                let c = v8::Uint8Array::new(scope, arg1, 0, length).unwrap();

                let arg2 = v8::Local::new(scope, c).into();

                function.call(scope, this, &[arg2]);
            }
        }
        drop(timing_guard);

        Ok(())
    };

    let span = info_span!("eval javascript");
    let timing_guard = span.enter();
    sys.block_on(async move { runtime::xyz(worker, main_module, foo).await })?;
    drop(timing_guard);

    // step 13 receive the callback
    // If I understood which combination of run_event_loop was required to execute
    // the javascript to completion then we should have something in our mailbox by
    // now. Another way to do this would be with an Arc. This will panic if the
    // mailbox is currently borrowed
    match mailbox.replace(None) {
        Some(Ok(buffer)) => match output {
            None => {
                io::stdout()
                    .write_all(&buffer)
                    .map_err(|io_err| CompilerError::WriteOutputFailed(io_err, "stdout".into()))?;
            }
            Some(filename) => {
                let mut f = fs::File::create(&filename)
                    .map_err(|io_err| CompilerError::WriteOutputFailed(io_err, filename))?;

                f.write_all(&buffer)
                    .map_err(|io_err| CompilerError::WriteOutputFailed(io_err, "stdout".into()))?;
            }
        },
        Some(Err(problem)) => {
            println!("had a problem {}", problem);
        }
        None => println!("nothing in the mailbox"),
    }

    if let Some(thread_handle) = sql_background_thread_handle {
        thread_handle.join().unwrap();
    }

    Ok(())
}

type OutputMailbox = Arc<RefCell<Option<Result<Vec<u8>, String>>>>;

#[deno_core::op]
fn op_starmelon_problem(
    state: &mut deno_core::OpState,
    msg: String,
) -> Result<(), deno_core::error::AnyError> {
    eprintln!("got problem from v8 runtime {:?}", &msg);
    let mailbox_clone = state.borrow::<OutputMailbox>();
    if let Ok(mut mailbox) = mailbox_clone.try_borrow_mut() {
        mailbox.replace(Err(msg));
    }
    Ok(())
}

#[deno_core::op]
fn op_starmelon_bytes_output(
    state: &mut OpState,
    msg: ElmResult<deno_core::ZeroCopyBuf, String>,
) -> Result<(), deno_core::error::AnyError> {
    let mailbox_clone = state.borrow::<OutputMailbox>();
    if let Ok(mut mailbox) = mailbox_clone.try_borrow_mut() {
        match msg {
            ElmResult::Ok { a: buffer } => {
                let slice: &[u8] = &buffer;
                mailbox.replace(Ok(slice.to_owned()));
            }
            ElmResult::Err { a: err } => {
                mailbox.replace(Err(err));
            }
        }
    }
    Ok(())
}

#[deno_core::op]
fn op_starmelon_string_output(
    state: &mut OpState,
    msg: ElmResult<String, String>,
) -> Result<(), deno_core::error::AnyError> {
    let mailbox_clone = state.borrow::<OutputMailbox>();
    if let Ok(mut mailbox) = mailbox_clone.try_borrow_mut() {
        match msg {
            ElmResult::Ok { a: s } => mailbox.replace(Ok(s.into_bytes())),
            ElmResult::Err { a: err } => mailbox.replace(Err(err)),
        };
    }
    Ok(())
}

#[derive(Debug, Copy, Clone)]
pub enum InputType {
    Value,
    String,
    Bytes,
}

pub enum ValidatedInput {
    String(String),
    Value(String),
    Bytes(Vec<u8>),
}

#[derive(Debug, Copy, Clone)]
pub enum OutputType {
    Html,
    String,
    Bytes,
    Value,
}

pub(crate) fn resolve_function_type(
    tipe: &elmi::Type,
) -> Result<(Option<InputType>, OutputType), TypeError> {
    match tipe {
        elmi::Type::TLambda(a, b) => {
            // We want to check the output types first because this is where we will figure out if
            // there is more than one argument
            let output_type = resolve_output_type(&**b)?;
            let input_type = resolve_input_type(&**a)?;

            Ok((Some(input_type), output_type))
        }
        elmi::Type::TVar(_) => Err(TypeError::CantEvalGeneric),
        elmi::Type::TType(module_name, name, args) if args.is_empty() => {
            // If our function returns a primitive type
            if module_name == "elm/core/String" && name == "String" {
                return Ok((None, OutputType::String));
            }
            if module_name == "elm/bytes/Bytes" && name == "Bytes" {
                return Ok((None, OutputType::String));
            }

            Err(TypeError::CantEvalType(tipe.clone()))
        }
        elmi::Type::TType(module_name, name, _args) => {
            if module_name == "elm/virtual-dom/VirtualDom" && name == "Node" {
                return Ok((None, OutputType::Html));
            }
            eprintln!("found this type {:?} {:?}", module_name, name);
            Err(TypeError::CantEvalCustomType)
        }
        elmi::Type::TRecord(_, _) => Err(TypeError::CantEvalRecord),
        elmi::Type::TUnit => Err(TypeError::CantEvalUnit),
        elmi::Type::TTuple(_, _, _) => Err(TypeError::CantEvalTuple),
        elmi::Type::TAlias(_, _, _, ref alias) => {
            match &**alias {
                elmi::AliasType::Filled(tipe) => {
                    // I think the recursion is limited to a single step. I have not tested what
                    // the CannonicalAnnotation would look like for a doubly indirect alias, for
                    // example for `view` below
                    // ```elm
                    // type alias Foo = Int
                    // type alias Bar = String
                    //
                    // type alias Zap = Foo -> Bar
                    //
                    // view : Zap
                    // ```
                    resolve_function_type(tipe)
                }
                elmi::AliasType::Holey(_) => return Err(TypeError::CantEvalHoleyAlias),
            }
        }
    }
}

fn resolve_input_type(tipe: &elmi::Type) -> Result<InputType, TypeError> {
    match tipe {
        elmi::Type::TLambda(_, _) => Err(TypeError::EvalRequiresSingleArgument(tipe.clone())),
        elmi::Type::TType(module_name, name, args) if args.is_empty() => {
            if module_name == "elm/core/String" && name == "String" {
                Ok(InputType::String)
            } else if module_name == "elm/bytes/Bytes" && name == "Bytes" {
                Ok(InputType::Bytes)
            } else if module_name == "elm/json/Json.Encode" && name == "Value" {
                Ok(InputType::Value)
            } else {
                Err(TypeError::InputTypeNotSupported(tipe.clone()))
            }
        }
        elmi::Type::TAlias(_, _, _, ref alias) => match &**alias {
            elmi::AliasType::Filled(tipe) => resolve_input_type(tipe),
            elmi::AliasType::Holey(_) => Err(TypeError::CantEvalHoleyAlias),
        },
        _ => Err(TypeError::OutputTypeNotSupported(tipe.clone())),
    }
}

fn resolve_output_type(tipe: &elmi::Type) -> Result<OutputType, TypeError> {
    match tipe {
        elmi::Type::TType(module_name, name, _args) => {
            if module_name == "elm/core/String" && name == "String" {
                Ok(OutputType::String)
            } else if module_name == "elm/bytes/Bytes" && name == "Bytes" {
                Ok(OutputType::Bytes)
            } else if module_name == "elm/json/Json.Encode" && name == "Value" {
                Ok(OutputType::Value)
            } else if module_name == "elm/virtual-dom/VirtualDom" && name == "Node" {
                Ok(OutputType::Html)
            } else {
                Err(TypeError::OutputTypeNotSupported(tipe.clone()))
            }
        }
        elmi::Type::TAlias(_, _, _, ref alias) => match &**alias {
            elmi::AliasType::Filled(tipe) => resolve_output_type(tipe),
            elmi::AliasType::Holey(_) => Err(TypeError::CantEvalHoleyAlias),
        },
        _ => Err(TypeError::OutputTypeNotSupported(tipe.clone())),
    }
}