use std::{borrow::Cow, collections::HashMap};

use fxprof_processed_profile::{
    CategoryHandle, CpuDelta, Frame, FrameFlags, FrameInfo, MarkerTiming, ProcessHandle, Profile,
    ReferenceTimestamp, SamplingInterval, StackHandle, StaticSchemaMarker, StringHandle,
    ThreadHandle, Timestamp,
};

use crate::profiler::state::{ProgramState, RESET_CODE, StackFrame};

pub struct Recording {
    profile: Profile,
    process: ProcessHandle,
    threads: HashMap<u16, ThreadHandle>,
    now: u64,
}

impl Recording {
    pub fn new(state: &ProgramState) -> Self {
        let reference_timestamp = ReferenceTimestamp::from_millis_since_unix_epoch(0.0);
        let interval = SamplingInterval::from_hz(20_000_000.0);
        let mut profile = Profile::new(state.name(), reference_timestamp, interval);

        let process =
            profile.add_process(state.name(), 1, Timestamp::from_nanos_since_reference(0));

        let lib = profile.add_lib(state.library_info().clone());
        profile.add_lib_mapping(process, lib, 0x00000000, 0xffffffff, 0);

        let mut me = Self {
            profile,
            process,
            threads: HashMap::new(),
            now: 0,
        };
        me.track_elapsed_cycles(state, 0);
        me
    }

    pub fn track_elapsed_cycles(&mut self, state: &ProgramState, cycles: u32) {
        self.now += cycles as u64;
        let timestamp = Timestamp::from_nanos_since_reference(self.now * 50);
        let weight = 1;

        let active_code = if let Some((code, frames)) = state.current_stack() {
            let thread = *self.threads.entry(code).or_insert_with(|| {
                let process = self.process;
                let tid = code as u32;
                let start_time = Timestamp::from_nanos_since_reference(self.now * 50);
                let is_main = code == RESET_CODE;
                let thread = self.profile.add_thread(process, tid, start_time, is_main);
                self.profile
                    .set_thread_name(thread, &thread_name_for_code(code));
                thread
            });

            let stack = self.handle_for_stack(thread, frames);
            let cpu_delta = CpuDelta::from_nanos((self.now - cycles as u64) * 50);
            self.profile
                .add_sample(thread, timestamp, stack, cpu_delta, weight);
            Some(code)
        } else {
            None
        };
        for (code, thread) in &self.threads {
            if active_code == Some(*code) {
                continue;
            }
            self.profile
                .add_sample_same_stack_zero_cpu(*thread, timestamp, weight);
        }
    }

    pub fn track_marker(&mut self, name: Cow<'static, str>) {
        let Some(thread) = self.threads.get(&RESET_CODE) else {
            return;
        };
        let timing = MarkerTiming::Instant(Timestamp::from_nanos_since_reference(self.now * 50));
        let marker = SimpleMarker(name);
        self.profile.add_marker(*thread, timing, marker);
    }

    pub fn finish(self) -> Vec<u8> {
        serde_json::to_vec(&self.profile).expect("could not serialize profile")
    }

    fn handle_for_stack(
        &mut self,
        thread: ThreadHandle,
        frames: &[StackFrame],
    ) -> Option<StackHandle> {
        let frames = frames
            .iter()
            .map(|f| {
                let frame = match f {
                    StackFrame::Address(address) => Frame::InstructionPointer(*address as u64),
                    StackFrame::Label(label) => Frame::Label(self.profile.intern_string(label)),
                };
                FrameInfo {
                    frame,
                    category_pair: CategoryHandle::OTHER.into(),
                    flags: FrameFlags::empty(),
                }
            })
            .collect::<Vec<_>>();
        self.profile.intern_stack_frames(thread, frames.into_iter())
    }
}

struct SimpleMarker(Cow<'static, str>);

impl StaticSchemaMarker for SimpleMarker {
    const UNIQUE_MARKER_TYPE_NAME: &'static str = "Simple";
    const FIELDS: &'static [fxprof_processed_profile::StaticSchemaMarkerField] = &[];

    fn name(&self, profile: &mut Profile) -> StringHandle {
        profile.intern_string(&self.0)
    }

    fn category(&self, _profile: &mut Profile) -> CategoryHandle {
        CategoryHandle::OTHER
    }

    fn string_field_value(&self, _field_index: u32) -> StringHandle {
        unreachable!()
    }

    fn number_field_value(&self, _field_index: u32) -> f64 {
        unreachable!()
    }
}

fn thread_name_for_code(code: u16) -> std::borrow::Cow<'static, str> {
    match code {
        RESET_CODE => "Main".into(),
        0xffd0 => "Duplexed exception".into(),
        0xfe40 => "VIP interrupt".into(),
        0xfe30 => "Communication interrupt".into(),
        0xfe20 => "Game pak interrupt".into(),
        0xfe10 => "Timer interrupt".into(),
        0xfe00 => "Game pad interrupt".into(),
        0xffc0 => "Address trap".into(),
        0xffa0..0xffc0 => format!("Trap (vector {})", code - 0xffa0).into(),
        0xff90 => "Illegal opcode exception".into(),
        0xff80 => "Zero division exception".into(),
        0xff60 => "Floating-point reserved operand exception".into(),
        0xff70 => "Floating-point invalid operation exception".into(),
        0xff68 => "Floating-point zero division exception".into(),
        0xff64 => "Floating-point overflow exception".into(),
        other => format!("Unrecognized handler (0x{other:04x})").into(),
    }
}