//! The `gc-trace` command line.
//!
//! ```text
//! gc-trace compare-tfrag-light <unpacked-dir> --level N <src>
//! gc-trace info        <src>
//! gc-trace dump-ee     <src> [--out FILE]
//! gc-trace find        <src> --bytes HEX
//! gc-trace read        <src> --addr HEX --len N
//! gc-trace pine-info
//! gc-trace pine-savestate SLOT
//! ```
//!
//! `<src>` is where the memory comes from, and it is one of:
//!
//! | Flag | Reads |
//! |---|---|
//! | `--state FILE` | a PCSX2 `.p2s` savestate |
//! | `--state latest` | the newest state in PCSX2's folder |
//! | `--ee FILE` | a raw 32 MiB EE RAM dump |
//! | `--pine [slot]` | the running emulator over PINE |

use std::path::PathBuf;

use anyhow::{anyhow, Context, Result};

use gc_trace::ee::EeRam;
use gc_trace::{compare, LevelInputs};

fn main() {
    let args: Vec<String> = std::env::args().skip(1).collect();
    match run(&args) {
        Ok(code) => std::process::exit(code),
        Err(e) => {
            eprintln!("error: {e:#}");
            std::process::exit(1);
        }
    }
}

/// Returns the process exit code.
fn run(args: &[String]) -> Result<i32> {
    let Some(cmd) = args.first() else {
        print!("{USAGE}");
        return Ok(0);
    };
    match cmd.as_str() {
        "info" => {
            let src = Source::parse(&args[1..])?;
            info(&src)
        }
        "dump-ee" => {
            let (src, rest) = Source::parse_with_rest(&args[1..])?;
            let out = flag(&rest, "--out").unwrap_or_else(|| "ee.bin".into());
            dump_ee(&src, &out)
        }
        "find" => {
            let (src, rest) = Source::parse_with_rest(&args[1..])?;
            let hex = require(&rest, "--bytes")?;
            find(&src, &hex)
        }
        "read" => {
            let (src, rest) = Source::parse_with_rest(&args[1..])?;
            let addr = require(&rest, "--addr")?;
            let len = require(&rest, "--len")?;
            read(&src, &addr, &len)
        }
        "verify-overlay-base" => {
            // gc-trace verify-overlay-base <unpacked-dir> <level> <src>
            let (src, rest) = Source::parse_with_rest(&args[1..])?;
            let (dir, level) = match rest.as_slice() {
                [dir, level, ..] => (PathBuf::from(dir), level.parse::<usize>().context("level")?),
                _ => {
                    return Err(anyhow!(
                        "usage: gc-trace verify-overlay-base <unpacked-dir> <level> <src>"
                    ))
                }
            };
            let overlay = std::fs::read(dir.join(format!("level{level}/overlay.bin")))
                .with_context(|| format!("level{level}/overlay.bin"))?;
            let bytes = src.load()?;
            let ram = EeRam::new(&bytes)?;
            let report = gc_trace::overlay_base::verify(&overlay, &ram)?;
            let mut text = String::new();
            gc_trace::overlay_base::print_report(&report, &mut text)?;
            println!("{text}");
            Ok(i32::from(!report.names.iter().all(|&b| b)))
        }
        "verify-tie-records" => {
            // gc-trace verify-tie-records <unpacked-dir> <level> <class> <lod> <src>
            let (src, rest) = Source::parse_with_rest(&args[1..])?;
            let (dir, level, class, lod) = match rest.as_slice() {
                [dir, level, class, lod, ..] => (
                    PathBuf::from(dir),
                    level.parse::<usize>().context("level")?,
                    class.parse::<usize>().context("class")?,
                    lod.parse::<usize>().context("lod")?,
                ),
                _ => {
                    return Err(anyhow!(
                    "usage: gc-trace verify-tie-records <unpacked-dir> <level> <class> <lod> <src>"
                ))
                }
            };
            let idx = std::fs::read(dir.join(format!("level{level}/core_index.bin")))
                .with_context(|| format!("level{level}/core_index.bin"))?;
            let core = std::fs::read(dir.join(format!("level{level}/core_data.bin")))
                .with_context(|| format!("level{level}/core_data.bin"))?;
            let bytes = src.load()?;
            let ram = EeRam::new(&bytes)?;
            let report = gc_trace::tie_verify::verify(&idx, &core, class, lod, &ram)?;
            let mut text = String::new();
            gc_trace::tie_verify::print_report(&report, &mut text)?;
            println!("{text}");
            Ok(report.exit_code())
        }
        "compare-tfrag-light" => {
            let (src, rest) = Source::parse_with_rest(&args[1..])?;
            let dir = rest
                .first()
                .map(PathBuf::from)
                .ok_or_else(|| anyhow!("which unpacked level directory?"))?;
            let level: usize = flag(&rest, "--level")
                .unwrap_or_else(|| "0".into())
                .parse()
                .context("--level")?;
            compare_tfrag_light(&dir, level, &src)
        }
        "pine-info" => pine_info(),
        "pine-savestate" => {
            let slot: u8 = args
                .get(1)
                .ok_or_else(|| anyhow!("which slot?"))?
                .parse()
                .context("slot")?;
            pine_savestate(slot)
        }
        _ => {
            print!("{USAGE}");
            Ok(0)
        }
    }
}

const USAGE: &str = "\
usage: gc-trace <command> ...
  compare-tfrag-light <unpacked-dir> [--level N] <src>
  verify-tie-records <unpacked-dir> <level> <class> <lod> <src>
  verify-overlay-base <unpacked-dir> <level> <src>
  info <src>
  dump-ee <src> [--out FILE]
  find <src> --bytes HEX
  read <src> --addr HEX --len N
  pine-info
  pine-savestate SLOT

<src> is one of:
  --state FILE      a PCSX2 .p2s savestate
  --state latest    the newest state in PCSX2's folder
  --ee FILE         a raw 32 MiB EE RAM dump
  --pine [slot]     the running emulator over PINE
";

/// Where a memory image comes from.
enum Source {
    State(PathBuf),
    Latest,
    Raw(PathBuf),
    Pine(u32),
}

impl Source {
    /// The first three arguments after the command.
    fn parse(args: &[String]) -> Result<Source> {
        Ok(Self::parse_with_rest(args)?.0)
    }

    /// The source flag, and everything else.
    ///
    /// The flag may sit anywhere: the usage line puts the level directory
    /// first, which is the order people type, so a first-argument-only reader
    /// would reject its own documented invocation. Whatever is left after the
    /// flag and its value is passed back for the caller's own flags.
    fn parse_with_rest(args: &[String]) -> Result<(Source, Vec<String>)> {
        let Some(at) = args
            .iter()
            .position(|a| matches!(a.as_str(), "--state" | "--ee" | "--pine"))
        else {
            return Err(anyhow!("no source; pass --state FILE, --ee FILE or --pine"));
        };
        let (flag, tail) = (args[at].as_str(), &args[at + 1..]);
        let (src, used) = match flag {
            "--state" => {
                let v = tail
                    .first()
                    .ok_or_else(|| anyhow!("--state needs a path or `latest`"))?;
                let src = if v == "latest" {
                    Source::Latest
                } else {
                    Source::State(PathBuf::from(v))
                };
                (src, 1)
            }
            "--ee" => {
                let v = tail.first().ok_or_else(|| anyhow!("--ee needs a path"))?;
                (Source::Raw(PathBuf::from(v)), 1)
            }
            // `--pine [slot]`: a following slot number is consumed, and
            // anything else -- a directory, another flag -- is not.
            _ => {
                let slot = match tail.first() {
                    Some(s) if s.parse::<u32>().is_ok() => s.parse()?,
                    _ => gc_trace::pine::DEFAULT_SLOT,
                };
                let used = usize::from(tail.first().is_some_and(|s| s.parse::<u32>().is_ok()));
                (Source::Pine(slot), used)
            }
        };
        let mut rest: Vec<String> = args[..at].to_vec();
        rest.extend_from_slice(&tail[used..]);
        Ok((src, rest))
    }

    /// Load the RAM image this source names.
    fn load(&self) -> Result<Vec<u8>> {
        match self {
            Source::State(p) => gc_trace::Savestate::open(p)
                .and_then(|s| s.ee_ram_owned())
                .with_context(|| format!("savestate {}", p.display())),
            Source::Latest => {
                let p = latest_state()?;
                let bytes = gc_trace::Savestate::open(&p).and_then(|s| s.ee_ram_owned());
                bytes.with_context(|| format!("savestate {} (latest)", p.display()))
            }
            Source::Raw(p) => {
                let b = std::fs::read(p).with_context(|| format!("read {}", p.display()))?;
                Ok(b)
            }
            Source::Pine(slot) => gc_trace::pine::Pine::connect_slot(*slot)
                .and_then(|p| p.dump_ee())
                .context("PINE dump"),
        }
    }
}

fn latest_state() -> Result<PathBuf> {
    let dir = pcsx2_state_dir();
    let mut newest: Option<(std::time::SystemTime, PathBuf)> = None;
    for entry in std::fs::read_dir(&dir).into_iter().flatten().flatten() {
        let p = entry.path();
        if p.extension().map(|e| e == "p2s").unwrap_or(false) {
            if let Ok(meta) = entry.metadata() {
                if let Ok(t) = meta.modified() {
                    if newest.as_ref().is_none_or(|(nt, _)| t > *nt) {
                        newest = Some((t, p));
                    }
                }
            }
        }
    }
    newest
        .map(|(_, p)| p)
        .ok_or_else(|| anyhow!("no .p2s savestates in {}", dir.display()))
}

/// PCSX2's savestate folder, per platform.
fn pcsx2_state_dir() -> PathBuf {
    if cfg!(target_os = "macos") {
        let home = std::env::var("HOME").unwrap_or_else(|_| ".".into());
        PathBuf::from(home).join("Library/Application Support/PCSX2/sstates")
    } else {
        let base = std::env::var_os("XDG_CONFIG_HOME")
            .map(PathBuf::from)
            .unwrap_or_else(|| {
                let home = std::env::var("HOME").unwrap_or_else(|_| ".".into());
                PathBuf::from(home).join(".config")
            });
        base.join("PCSX2/sstates")
    }
}

fn info(src: &Source) -> Result<i32> {
    match src {
        Source::State(p) => info_state(p)?,
        Source::Latest => info_state(&latest_state()?)?,
        Source::Raw(_) => {
            let bytes = src.load()?;
            let ram = EeRam::new(&bytes)?;
            println!("raw EE RAM image, {} bytes", ram.bytes().len());
        }
        Source::Pine(slot) => {
            let pine = gc_trace::pine::Pine::connect_slot(*slot)?;
            println!("PINE: version {}", pine.version()?);
            println!("PINE: title {}", pine.title()?);
        }
    }
    Ok(0)
}

fn info_state(p: &std::path::Path) -> Result<()> {
    let state = gc_trace::Savestate::open(p)?;
    println!(
        "{}: v{:#010x} build {}",
        p.display(),
        state.version.unwrap_or(0),
        state.build
    );
    for e in state.entries() {
        println!("  {e}");
    }
    Ok(())
}

fn dump_ee(src: &Source, out: &str) -> Result<i32> {
    let bytes = src.load()?;
    let ram = EeRam::new(&bytes)?;
    std::fs::write(out, ram.bytes()).with_context(|| format!("write {out}"))?;
    println!("wrote {} bytes to {out}", ram.bytes().len());
    Ok(0)
}

fn find(src: &Source, hex: &str) -> Result<i32> {
    let bytes = src.load()?;
    let ram = EeRam::new(&bytes)?;
    let needle = parse_hex(hex)?;
    for at in ram.find_all(&needle) {
        println!("{at:#x}");
    }
    Ok(0)
}

fn read(src: &Source, addr_hex: &str, len_hex: &str) -> Result<i32> {
    let bytes = src.load()?;
    let ram = EeRam::new(&bytes)?;
    let addr = usize::from_str_radix(addr_hex.trim_start_matches("0x"), 16)?;
    let len = usize::from_str_radix(len_hex.trim_start_matches("0x"), 16)?;
    let slice = ram
        .slice(addr, len)
        .ok_or_else(|| anyhow!("{addr:#x}+{len:#x} runs past the RAM image"))?;
    for (i, row) in slice.chunks(16).enumerate() {
        let hex: Vec<String> = row.iter().map(|b| format!("{b:02x}")).collect();
        println!("{:08x}  {}", addr + i * 16, hex.join(" "));
    }
    Ok(0)
}

fn compare_tfrag_light(dir: &std::path::Path, level: usize, src: &Source) -> Result<i32> {
    let inputs = LevelInputs::load(dir, level)?;
    let bytes = src.load()?;
    let ram = EeRam::new(&bytes)?;
    let report = compare(&inputs, level, &ram)?;
    let mut text = String::new();
    gc_trace::print_report(&report, &mut text)?;
    println!("{text}");
    Ok(report.exit_code())
}

fn pine_info() -> Result<i32> {
    let pine = gc_trace::pine::Pine::connect()?;
    println!("version: {}", pine.version()?);
    println!("title:   {}", pine.title()?);
    println!(
        "PINE is up on {}",
        gc_trace::pine::socket_path(gc_trace::pine::DEFAULT_SLOT).display()
    );
    Ok(0)
}

fn pine_savestate(slot: u8) -> Result<i32> {
    let pine = gc_trace::pine::Pine::connect()?;
    pine.save_state(slot)?;
    println!("savestate requested for slot {slot}");
    Ok(0)
}

/// Parse `hex` bytes, ignoring whitespace.
fn parse_hex(s: &str) -> Result<Vec<u8>> {
    let compact: String = s.chars().filter(|c| !c.is_whitespace()).collect();
    if compact.len() % 2 != 0 {
        return Err(anyhow!("hex string has an odd length"));
    }
    (0..compact.len())
        .step_by(2)
        .map(|i| u8::from_str_radix(&compact[i..i + 2], 16).map_err(Into::into))
        .collect()
}

/// Look up `--flag VALUE` in the rest.
fn flag(args: &[String], name: &str) -> Option<String> {
    let at = args.iter().position(|a| a == name)?;
    args.get(at + 1).cloned()
}

fn require(args: &[String], name: &str) -> Result<String> {
    flag(args, name).ok_or_else(|| anyhow!("missing {name}"))
}