//! Headless runner for testing: `daedalian --headless OUT_DIR SCRIPT...`
//! Script tokens: `N` run N frames; `BUTTON:N` hold a button for N frames
//! (up down left right a b start select); `shot:NAME` save OUT_DIR/NAME.png.
//! All audio is written to OUT_DIR/audio.wav.

use crate::machine::*;
use std::fs;
use std::path::Path;

fn crc32(data: &[u8]) -> u32 {
    let mut crc = 0xFFFF_FFFFu32;
    for &b in data {
        crc ^= b as u32;
        for _ in 0..8 {
            crc = if crc & 1 != 0 { 0xEDB8_8320 ^ (crc >> 1) } else { crc >> 1 };
        }
    }
    !crc
}

fn write_png(path: &Path, w: usize, h: usize, gray: &[u8]) {
    let mut raw = Vec::new();
    for y in 0..h {
        raw.push(0);
        raw.extend_from_slice(&gray[y * w..(y + 1) * w]);
    }
    // zlib stream with stored (uncompressed) deflate blocks
    let mut z = vec![0x78, 0x01];
    for (i, chunk) in raw.chunks(65535).enumerate() {
        let last = (i + 1) * 65535 >= raw.len();
        z.push(last as u8);
        z.extend_from_slice(&(chunk.len() as u16).to_le_bytes());
        z.extend_from_slice(&(!(chunk.len() as u16)).to_le_bytes());
        z.extend_from_slice(chunk);
    }
    let (mut a, mut b) = (1u32, 0u32);
    for &x in &raw {
        a = (a + x as u32) % 65521;
        b = (b + a) % 65521;
    }
    z.extend_from_slice(&(b << 16 | a).to_be_bytes());
    let mut png = b"\x89PNG\r\n\x1a\n".to_vec();
    let mut chunk = |t: &[u8], d: &[u8]| {
        png.extend_from_slice(&(d.len() as u32).to_be_bytes());
        let mut td = t.to_vec();
        td.extend_from_slice(d);
        png.extend_from_slice(&td);
        png.extend_from_slice(&crc32(&td).to_be_bytes());
    };
    let mut ihdr = Vec::new();
    ihdr.extend_from_slice(&(w as u32).to_be_bytes());
    ihdr.extend_from_slice(&(h as u32).to_be_bytes());
    ihdr.extend_from_slice(&[8, 0, 0, 0, 0]);
    chunk(b"IHDR", &ihdr);
    chunk(b"IDAT", &z);
    chunk(b"IEND", &[]);
    fs::write(path, png).unwrap();
}

fn write_wav(path: &Path, rate: u32, samples: &[f32]) {
    let mut d = Vec::new();
    let data_len = samples.len() as u32 * 2;
    d.extend_from_slice(b"RIFF");
    d.extend_from_slice(&(36 + data_len).to_le_bytes());
    d.extend_from_slice(b"WAVEfmt ");
    d.extend_from_slice(&16u32.to_le_bytes());
    d.extend_from_slice(&1u16.to_le_bytes());
    d.extend_from_slice(&2u16.to_le_bytes());
    d.extend_from_slice(&rate.to_le_bytes());
    d.extend_from_slice(&(rate * 4).to_le_bytes());
    d.extend_from_slice(&4u16.to_le_bytes());
    d.extend_from_slice(&16u16.to_le_bytes());
    d.extend_from_slice(b"data");
    d.extend_from_slice(&data_len.to_le_bytes());
    for s in samples {
        d.extend_from_slice(&((s.clamp(-1.0, 1.0) * 32767.0) as i16).to_le_bytes());
    }
    fs::write(path, d).unwrap();
}

pub fn run(rom: &[u8], args: &[String]) {
    let out = Path::new(&args[0]);
    fs::create_dir_all(out).unwrap();
    let rate = 44_100;
    let mut m = Machine::new(rom, rate);
    let mut audio = Vec::new();
    let mut frames = 0u64;
    let run = |m: &mut Machine, n: u64, audio: &mut Vec<f32>, frames: &mut u64| {
        for _ in 0..n {
            m.run_frame();
            audio.append(&mut m.apu.out);
            *frames += 1;
        }
    };
    for tok in &args[1..] {
        if let Ok(n) = tok.parse::<u64>() {
            run(&mut m, n, &mut audio, &mut frames);
        } else if let Some(name) = tok.strip_prefix("shot:") {
            let gray: Vec<u8> = m.framebuffer.iter().map(|&s| [0xFF, 0xAA, 0x55, 0x00][s as usize]).collect();
            write_png(&out.join(format!("{name}.png")), SCREEN_W, SCREEN_H, &gray);
            println!("frame {frames}: {name}.png (pc ${:04X})", m.pc);
        } else if let Some(spec) = tok.strip_prefix("goto:") {
            // steer the puzzle cursor (wPieceY/wPieceX at $C0A1/$C0A2) to a position
            let (ty, tx) = spec.split_once(':').unwrap();
            let (ty, tx) = (u8::from_str_radix(ty, 16).unwrap(), u8::from_str_radix(tx, 16).unwrap());
            for _ in 0..100 {
                let (cy, cx) = (m.r8(0xC0A1), m.r8(0xC0A2));
                let bit = if cy < ty { BTN_DOWN } else if cy > ty { BTN_UP }
                    else if cx < tx { BTN_RIGHT } else if cx > tx { BTN_LEFT } else { break };
                m.buttons |= bit;
                run(&mut m, 1, &mut audio, &mut frames);
                m.buttons &= !bit;
                run(&mut m, 5, &mut audio, &mut frames);
            }
        } else if let Some(spec) = tok.strip_prefix("peek:") {
            let (addr, n) = spec.split_once(':').unwrap_or((spec, "1"));
            let addr = u16::from_str_radix(addr, 16).unwrap();
            let vals: Vec<String> = (0..n.parse::<u16>().unwrap())
                .map(|i| format!("{:02X}", m.r8(addr + i)))
                .collect();
            println!("frame {frames}: ${addr:04X}: {}", vals.join(" "));
        } else if let Some((btn, n)) = tok.split_once(':') {
            let bit = match btn {
                "up" => BTN_UP, "down" => BTN_DOWN, "left" => BTN_LEFT, "right" => BTN_RIGHT,
                "a" => BTN_A, "b" => BTN_B, "start" => BTN_START, "select" => BTN_SELECT,
                _ => panic!("unknown token {tok}"),
            };
            m.buttons |= bit;
            run(&mut m, n.parse().unwrap(), &mut audio, &mut frames);
            m.buttons &= !bit;
        } else {
            panic!("unknown token {tok}");
        }
    }
    write_wav(&out.join("audio.wav"), rate, &audio);
    println!("{frames} frames, {:.1}s of audio", audio.len() as f32 / 2.0 / rate as f32);
}