//! Non-interactive command-line interface, intended for scripting and for
//! driving the patcher from another application.
//!
//! Contract: the process exit code is authoritative — `0` success, `1` a
//! patch/runtime error, `2` a usage error. The whole command line is
//! validated before any patch work starts. With `--json`, the final line of
//! stdout is a single JSON object (`{"ok":true,"command":...,"output":...}`
//! or `{"ok":false,"error":...}`), usage errors included; human progress is
//! printed before it.
use crate::patch::{
    ace,
    dispatch::{Target, android, windows},
    hoyokprotect, protection, rsa,
};
use anyhow::Result;
use std::{collections::HashMap, path::PathBuf, process::ExitCode};

const USAGE: &str = "\
Honkai Impact 3rd patcher

Usage:
  Hi3-Patcher                 Launch the interactive menu
  Hi3-Patcher <command> [options]

Commands:
  dispatch   Redirect dispatch & SDK URLs to a server
             --platform <windows|android>  --input <path>
             --server <host[:port]>  [--https]
  rsa        Replace the passport RSA public key
             --platform <windows|android>  --input <path>  [--key <base64>]
  ace        Remove ACE from a Windows client (<= 8.9); requires a capture
             --input <BH3.exe|folder>  [--yes]
  hoyok      Disable HoYoKProtect in a Windows client (9.0+)
             --input <BH3.exe|folder>
  protection Remove Android protection and re-sign the APK
             --input <app.apk>  [--variant <ano|tss|auto>]

Options:
  --json     Emit a single JSON result object as the last stdout line
  -h, --help, -V, --version

Windows --input accepts the game folder or its BH3.exe.
rsa --key defaults to the PemukulPaku public key when omitted.";

/// Options each command accepts: `(value options, switches)`. Every command
/// also accepts `--json`.
fn accepted(command: &str) -> Option<(&'static [&'static str], &'static [&'static str])> {
    Some(match command {
        "dispatch" => (&["platform", "input", "server"], &["https"]),
        "rsa" => (&["platform", "input", "key"], &[]),
        "ace" => (&["input"], &["yes"]),
        "hoyok" => (&["input"], &[]),
        "protection" => (&["input", "variant"], &[]),
        _ => return None,
    })
}

struct Parsed {
    values: HashMap<String, String>,
    switches: Vec<String>,
}

/// Split `--name value`, `--name=value` and `--switch` tokens, rejecting
/// anything the command does not accept. Errors are usage errors.
fn parse(command: &str, rest: &[String]) -> Result<Parsed, String> {
    let (options, flags) =
        accepted(command).ok_or_else(|| format!("unknown command: {command}"))?;
    let mut values = HashMap::new();
    let mut switches: Vec<String> = Vec::new();
    let mut it = rest.iter();
    while let Some(token) = it.next() {
        let Some(name) = token.strip_prefix("--") else {
            return Err(format!("unexpected argument: {token}"));
        };
        let (name, inline) = match name.split_once('=') {
            Some((name, value)) => (name, Some(value)),
            None => (name, None),
        };
        if name == "json" || flags.contains(&name) {
            if inline.is_some() {
                return Err(format!("--{name} does not take a value"));
            }
            if switches.iter().any(|s| s == name) {
                return Err(format!("--{name} given more than once"));
            }
            switches.push(name.to_owned());
        } else if options.contains(&name) {
            let value = match inline {
                Some(value) => value.to_owned(),
                None => it
                    .next()
                    .filter(|value| !value.starts_with("--"))
                    .ok_or_else(|| format!("--{name} needs a value"))?
                    .clone(),
            };
            if values.insert(name.to_owned(), value).is_some() {
                return Err(format!("--{name} given more than once"));
            }
        } else {
            return Err(format!("{command} does not accept --{name}"));
        }
    }
    Ok(Parsed { values, switches })
}

impl Parsed {
    fn required(&self, name: &str) -> Result<&str, String> {
        match self.values.get(name).map(String::as_str) {
            None | Some("") => Err(format!("--{name} is required")),
            Some(value) => Ok(value),
        }
    }
    fn has(&self, name: &str) -> bool {
        self.switches.iter().any(|s| s == name)
    }
}

enum Platform {
    Windows,
    Android,
}

enum Variant {
    Auto,
    Ano,
    Tss,
}

/// A fully validated command, ready to run.
enum Job {
    Dispatch { platform: Platform, input: PathBuf, target: Target },
    Rsa { platform: Platform, input: PathBuf, key: String },
    Ace { input: PathBuf, yes: bool },
    Hoyok { input: PathBuf },
    Protection { input: PathBuf, variant: Variant },
}

fn parse_platform(args: &Parsed) -> Result<Platform, String> {
    match args.required("platform")? {
        "windows" | "win" => Ok(Platform::Windows),
        "android" => Ok(Platform::Android),
        other => Err(format!("unknown platform: {other}")),
    }
}

/// Resolve `--input`; a Windows input may be the game folder or its BH3.exe.
fn input_path(args: &Parsed, platform: &Platform) -> Result<PathBuf, String> {
    let path = PathBuf::from(args.required("input")?);
    Ok(match platform {
        Platform::Windows if path.is_dir() => path.join("BH3.exe"),
        _ => path,
    })
}

/// Check a parsed command line per command. Errors are usage errors.
fn job(command: &str, args: &Parsed) -> Result<Job, String> {
    Ok(match command {
        "dispatch" => {
            let platform = parse_platform(args)?;
            let input = input_path(args, &platform)?;
            let target = Target::new(args.required("server")?, args.has("https"))
                .map_err(|error| format!("--server: {error:#}"))?;
            Job::Dispatch { platform, input, target }
        }
        "rsa" => {
            let platform = parse_platform(args)?;
            let input = input_path(args, &platform)?;
            let key = args.values.get("key").cloned().unwrap_or_default();
            rsa::public_body(&key).map_err(|error| format!("--key: {error:#}"))?;
            Job::Rsa { platform, input, key }
        }
        "ace" => Job::Ace {
            input: input_path(args, &Platform::Windows)?,
            yes: args.has("yes"),
        },
        "hoyok" => Job::Hoyok {
            input: input_path(args, &Platform::Windows)?,
        },
        "protection" => Job::Protection {
            input: input_path(args, &Platform::Android)?,
            variant: match args.values.get("variant").map(String::as_str) {
                None | Some("auto") => Variant::Auto,
                Some("ano") => Variant::Ano,
                Some("tss") => Variant::Tss,
                Some(other) => return Err(format!("unknown variant: {other}")),
            },
        },
        other => return Err(format!("unknown command: {other}")),
    })
}

/// Run a validated job. Returns the output path for Android patches.
fn execute(job: Job) -> Result<Option<PathBuf>> {
    Ok(match job {
        Job::Dispatch { platform: Platform::Windows, input, target } => {
            windows::patch(&input, &target)?;
            None
        }
        Job::Dispatch { platform: Platform::Android, input, target } => {
            Some(android::patch(&input, &target)?)
        }
        Job::Rsa { platform: Platform::Windows, input, key } => {
            rsa::patch_windows(&input, &key)?;
            None
        }
        Job::Rsa { platform: Platform::Android, input, key } => {
            Some(rsa::patch_android(&input, &key)?)
        }
        Job::Ace { input, yes } => {
            ace::patch(&input, |_| Ok(yes))?;
            None
        }
        Job::Hoyok { input } => {
            hoyokprotect::patch(&input)?;
            None
        }
        Job::Protection { input, variant } => Some(match variant {
            Variant::Auto => protection::auto(&input)?,
            Variant::Ano => protection::anosdk(&input)?,
            Variant::Tss => protection::mobile_ace_tss(&input)?,
        }),
    })
}

fn report(command: &str, result: Result<Option<PathBuf>>, json: bool) -> ExitCode {
    match result {
        Ok(output) => {
            let out = output.as_ref().map(|p| p.display().to_string());
            if json {
                println!(
                    "{}",
                    serde_json::json!({"ok": true, "command": command, "output": out})
                );
            } else if let Some(path) = out {
                println!("Output: {path}");
            }
            ExitCode::SUCCESS
        }
        Err(error) => {
            let message = format!("{error:#}");
            if json {
                println!("{}", serde_json::json!({"ok": false, "error": message}));
            } else {
                eprintln!("error: {message}");
            }
            ExitCode::FAILURE
        }
    }
}

fn usage_error(message: &str, json: bool) -> ExitCode {
    if json {
        println!("{}", serde_json::json!({"ok": false, "error": message}));
    } else {
        eprintln!("error: {message}\n\n{USAGE}");
    }
    ExitCode::from(2)
}

/// Entry point for a non-empty argument list (the command and its options).
pub fn run(argv: &[String]) -> ExitCode {
    let command = argv[0].as_str();
    let rest = &argv[1..];
    if matches!(command, "-h" | "--help" | "help")
        || rest.iter().any(|a| a == "-h" || a == "--help")
    {
        println!("{USAGE}");
        return ExitCode::SUCCESS;
    }
    if matches!(command, "-V" | "--version" | "version") {
        println!("Hi3-Patcher {}", env!("CARGO_PKG_VERSION"));
        return ExitCode::SUCCESS;
    }
    let json = rest.iter().any(|a| a == "--json");
    match parse(command, rest).and_then(|args| job(command, &args)) {
        Ok(job) => report(command, execute(job), json),
        Err(message) => usage_error(&message, json),
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    /// Validate a command line the way `run` does, without executing it.
    fn check(line: &[&str]) -> Result<Job, String> {
        let argv: Vec<String> = line.iter().map(|s| s.to_string()).collect();
        parse(&argv[0], &argv[1..]).and_then(|args| job(&argv[0], &args))
    }

    #[test]
    fn accepts_valid_command_lines() {
        let cases: &[&[&str]] = &[
            &["dispatch", "--platform", "windows", "--input", "x", "--server", "1.1.1.1"],
            &["dispatch", "--platform=android", "--input=a.apk", "--server=h:3000", "--https", "--json"],
            &["rsa", "--platform", "win", "--input", "x"],
            &["rsa", "--platform", "windows", "--input", "x", "--key", ""],
            &["ace", "--input", "x", "--yes"],
            &["hoyok", "--input", "x"],
            &["protection", "--input", "a.apk", "--variant", "tss"],
        ];
        for line in cases {
            assert!(check(line).is_ok(), "rejected: {line:?}");
        }
    }

    #[test]
    fn rejects_usage_errors() {
        let cases: &[&[&str]] = &[
            &["bogus"],
            &["dispatch", "--platform", "windows", "--input", "x"],
            &["dispatch", "--platform", "plan9", "--input", "x", "--server", "h"],
            &["dispatch", "--platform", "windows", "--input", "x", "--server", "h/p"],
            &["dispatch", "stray"],
            &["dispatch", "--input"],
            &["dispatch", "--input", "--json"],
            &["dispatch", "--platform", "windows", "--input", "x", "--server", "h", "--sever", "h"],
            &["rsa", "--platform", "windows", "--input", "x", "--key", "abc"],
            &["ace", "--input", "x", "--https"],
            &["ace", "--input", "a", "--input", "b"],
            &["ace", "--input", "x", "--yes=1"],
            &["hoyok", "--input", ""],
            &["protection", "--input", "a.apk", "--variant", "x"],
        ];
        for line in cases {
            assert!(check(line).is_err(), "accepted: {line:?}");
        }
    }
}