//! `wai-quantum repair`: a program repaired from its diagnostics, on the
//! lines they flag alone ([`wai_quantum::engine::repair`]). The repaired
//! program goes to standard output (or back to its file with `--write`), and
//! each repair and what needs a person to standard error; `--json` prints the
//! engine's whole answer, its verdict included.
//!
//! `--proposed FILE` checks a repair someone else wrote (a person's, an
//! agent's): it is taken only if it changes no line the diagnostics do not
//! flag. Exit 0 when the program reads, 1 when something still needs a
//! person, 2 when a proposal is rejected.

use serde_json::{Value, json};
use std::path::PathBuf;
use wai_quantum::engine::repair;

#[derive(clap::Args)]
pub struct Args {
    /// The program; `-` or nothing reads standard input
    pub file: Option<PathBuf>,
    /// A repaired version to check: taken only if it changes no line but those the diagnostics flag
    #[arg(long, value_name = "FILE")]
    pub proposed: Option<PathBuf>,
    /// The bound for an unbounded `while` on measured bits (Q310): it runs at most this many times
    #[arg(long, value_name = "N")]
    pub max_iterations: Option<u64>,
    /// Round each angle the bit-exact method refuses (Q500) to the nearest multiple of 2π/2^K, its rounding stated on its line
    #[arg(long, value_name = "K")]
    pub dyadic_bits: Option<u32>,
    /// A register's size, for one used before it is declared (Q102), as q=3 (repeatable)
    #[arg(long = "size", value_name = "NAME=N", value_parser = size_arg)]
    pub sizes: Vec<(String, u32)>,
    /// Only check the proposal: make none of the engine's own fixes
    #[arg(long)]
    pub no_rules: bool,
    /// Write the repaired program back to its file
    #[arg(long, conflicts_with = "json")]
    pub write: bool,
    /// Print the engine's answer as JSON: the program, each repair, what needs a person, and the verdict
    #[arg(long)]
    pub json: bool,
}

fn size_arg(s: &str) -> Result<(String, u32), String> {
    let (k, v) = s.split_once('=').ok_or("give a register and its size, as q=3")?;
    let n: u32 = v.trim().parse().map_err(|_| format!("{v}: a size is a whole number"))?;
    Ok((k.trim().to_string(), n))
}

/// The repair's choices as the engine takes them.
pub fn options(a: &Args, proposed: Option<String>) -> Value {
    let mut o = json!({});
    if let Some(n) = a.max_iterations {
        o["max_iterations"] = json!(n);
    }
    if let Some(k) = a.dyadic_bits {
        o["dyadic_bits"] = json!(k);
    }
    if !a.sizes.is_empty() {
        o["sizes"] = Value::Object(a.sizes.iter().map(|(k, n)| (k.clone(), json!(n))).collect());
    }
    if let Some(p) = proposed {
        o["proposed"] = json!(p);
    }
    if a.no_rules {
        o["rules"] = json!(false);
    }
    o
}

/// What was repaired and what needs a person, as a reader takes it in.
pub fn report(v: &Value) -> String {
    let mut s = String::new();
    for r in v["repairs"].as_array().into_iter().flatten() {
        let code = r["code"].as_str().unwrap_or("—");
        s += &format!("repaired  {code}: {}\n", r["rule"].as_str().unwrap_or(""));
        for e in r["edits"].as_array().into_iter().flatten() {
            let line = e["line"].as_u64().unwrap_or(0);
            match (e["before"].as_str(), e["after"].as_str()) {
                (Some(b), Some(a)) => s += &format!("  line {line}: {b}\n       → {a}\n"),
                (None, Some(a)) => s += &format!("  added before line {line}: {a}\n"),
                (Some(b), None) => s += &format!("  removed line {line}: {b}\n"),
                _ => {}
            }
        }
    }
    for p in v["needs_person"].as_array().into_iter().flatten() {
        s += &format!("needs a person  {}: {}\n  {}\n", p["code"].as_str().unwrap_or(""), p["message"].as_str().unwrap_or(""), p["advice"].as_str().unwrap_or(""));
    }
    s += &format!("verdict   {}: {}\n", v["verdict"]["level"].as_str().unwrap_or(""), v["verdict"]["statement"].as_str().unwrap_or(""));
    s
}

/// `wai-quantum repair`.
pub fn main(a: Args) {
    let src = crate::read_text(a.file.as_deref()).unwrap_or_else(|e| crate::die(&e));
    let proposed = a.proposed.as_deref().map(|p| crate::read_text(Some(p)).unwrap_or_else(|e| crate::die(&e)));
    let v = match repair::repair(&src, &options(&a, proposed)) {
        Ok(v) => v,
        Err(e) => {
            if a.json {
                println!("{}", json!({ "error": e, "refusal": wai_quantum::engine::refusal::refusal_json(&e) }));
            } else {
                eprintln!("wai-quantum: {e}");
            }
            std::process::exit(2);
        }
    };
    let text = v["qasm"].as_str().unwrap_or("");
    if a.json {
        println!("{v}");
    } else if a.write {
        let Some(path) = a.file.as_deref().filter(|p| *p != std::path::Path::new("-")) else { crate::die("--write needs the program's file") };
        if v["changed"] == true {
            std::fs::write(path, text).unwrap_or_else(|e| crate::die(&format!("{}: {e}", path.display())));
        }
        eprint!("{}", report(&v));
    } else {
        print!("{text}");
        eprint!("{}", report(&v));
    }
    std::process::exit(if v["ok"] == true { 0 } else { 1 });
}