//! `script.check`: a script written for the reference app (`.jsx`, `.jsxinc`, `.js`, or a compiled
//! `.jsxbin`) checked without running any of it, by `vectorcraft-scriptcheck`: what kind of file it
//! is, what it needs, its directives and includes, the platform features and document-model member
//! chains it uses, the menu commands it runs, what it does outside the document, and its problems.
//! With a path and `includes`, the files its `#include` lines name are read from inside its folder,
//! each through the same checks as every other file a command reads.

use serde_json::{Value, json};
use vectorcraft_scriptcheck::{Limits, Loaded, Loader, Report};

/// The ids a reply can hold, for the windows that show it.
pub use vectorcraft_scriptcheck::{IncludeStatus, Need, OUTSIDE, PROBLEMS};

use super::{CommandSpec, EngineError, Result, Session, always, bad, bool_or, cmd, str_param};
use crate::script;

/// The extensions of the scripts File › Open shows a check for.
pub const EXTS: &[&str] = &["jsx", "jsxinc", "jsxbin"];

/// The extensions of the scripts `script.run` takes as a file, in any case.
pub const RUN_EXTS: &[&str] = &["js", "jsx"];

/// Does `path` name a file `script.run` takes?
pub fn runs(path: &str) -> bool {
    std::path::Path::new(path).extension().and_then(|e| e.to_str()).is_some_and(|e| RUN_EXTS.iter().any(|x| e.eq_ignore_ascii_case(x)))
}

pub fn specs() -> Vec<CommandSpec> {
    vec![
        cmd!(
            query "script.run",
            "Run Script",
            [],
            None,
            "{path?: a .js or .jsx file | source?: the script's text (exactly one of the two), name?: the name errors and the report use (default: the path's file name, or \"script\"), args?: {…} (at most 1 MiB as JSON; vc.args in the script), answers?: {} (no prompts exist yet: only an empty object is taken), maxFuel?: whole number from 1 to 100000000000 (instructions in all; default 1000000000)} run a JavaScript file against the open documents, through the vc object: vc.run(id, params) runs a command and returns its result, a failed command throws an error the script can catch and puts back the documents and the session state it changed, while any file it wrote stays written and is named; vc.document is a snapshot of the active document or null; vc.commands lists the commands a script may run; vc.log(value) adds to the report; vc.args is args; vc.api.version and vc.api.has(feature) describe the API. The run is one transaction: on success each changed document gets one undo step, Run Script, and each preference it changed keeps its value, and on an uncaught error, a limit or script.stop every open document and the session go back as they were; files a command wrote before that stay written and are named. While it runs, other commands that change anything end with a busy error. Commands that change anything outside the documents (script.*, except script.check, plugin.*, prefs.*, actionSet.*, shortcutSet.*, help.*, print.*, library.*, importMatches.*, edit.undoGroup.*, file.recovery.*, stroke.widthProfile.*, saving, importing or deleting a preset, text.addFontFiles, text.findFontFiles, text.rescanFonts, links.findFiles, file.place.queue, color.loadProfile, color.removeProfile, file.print, view.proofSetup, view.proofColors, view.overprintPreview, view.separationsPreview) throw. VectorCraft's own limits: 8 MiB of source, 256 MiB of heap (128 MiB on the web), 2000000 host calls, 200000000 instructions without a pause, 64 levels, 16 MiB and 1048576 entries for a value crossing to or from a command, 10000 log entries and 4 MiB of log, and 100000 objects and 512 MiB of new document data, past which a person is asked to continue or stop and a run with nobody to ask ends → {ok: true, name, changed: [document names], written: [paths], log: [values], fuelUsed, hostCalls}, or, in the app, {running: true, name} and the report later in ui.inspect's scriptReport",
            always,
            run
        ),
        cmd!(
            query "script.stop",
            "Stop Script",
            [],
            None,
            "{} stop the running script, which puts every document back as it was before the run; asking again while it stops is harmless → {stopped: whether a script was running}",
            always,
            stop
        ),
        cmd!(
            query "script.check",
            "Check Script",
            [],
            None,
            "{path? | data?: the script's text | dataBase64?, name?: the file's name (default: the path's; with a path, only the reply's name), includes?: false (with a path: also check the files its #include lines name, inside the script's folder; not on the web)} check a script written for the reference app (.jsx, .jsxinc, .js, or a compiled .jsxbin) without running any of it → {name, kind: script|compiled|module|notText|tooLarge, needs: [language|dom|files|menuCommands|dialogs|hostOnly], lines, targets: [{value, app, instance?, version?, locale?, line, file?}], directives: [{name, value, line, form: \"#\"|\"//@\", file?}], includes: [{value, line, status: checked|missing|notFollowed|cycle|notRead|limit|unreadable, path?, file?}], features: [{id, count, lines}], dom: {members: [{path, count}], types: [{name, count}]}, menuCommands: {strings: [{value, count, lines}], dynamic}, outside: [{id: filesWritten|filesOpened|network|nativeCode|otherApps|environment|unseenCode|preferences, count, lines, modes?}], problems: [{code, line?, file?, detail?}], truncated} (file: the included file it is in; lines: at most 20 of the script's own, while counts include the included files; at most 8 MiB a file and 32 MiB in all, 64 included files 16 deep, 1,024 paths looked up for them, 1,000 entries a list, text echoed cut to 120 characters)",
            always,
            check
        ),
    ]
}

/// A refusal of `script.run`'s parameters, which only a program's own call can give.
fn param(msg: impl Into<String>) -> EngineError {
    EngineError::BadParams { cmd: "script.run".into(), msg: msg.into() }
}

/// `maxFuel`: a whole number from 1 to [`script::MAX_FUEL`], or the default when omitted.
fn max_fuel(p: &Value) -> Result<u64> {
    let Some(v) = p.get("maxFuel") else { return Ok(script::DEFAULT_FUEL) };
    v.as_u64()
        .filter(|n| (1..=script::MAX_FUEL).contains(n))
        .ok_or_else(|| param(format!("`maxFuel` must be a whole number from 1 to {}", script::MAX_FUEL)))
}

/// The text of a script read as bytes: a byte order mark is left out, and compiled scripts and
/// bytes that are not UTF-8 are refused.
fn script_text(bytes: &[u8]) -> Result<String> {
    if bytes.starts_with(b"@JSXBIN@") {
        return Err(EngineError::Other(COMPILED.to_string()));
    }
    let text = std::str::from_utf8(bytes).map_err(|_| EngineError::Other(NOT_TEXT.to_string()))?;
    Ok(text.strip_prefix('\u{feff}').unwrap_or(text).to_string())
}

const COMPILED: &str = "this is a compiled script, which cannot be run; use its source text";
const NOT_TEXT: &str = "the script is not UTF-8 text";
/// The error for a script over [`script::MAX_SOURCE_BYTES`].
pub const TOO_LARGE: &str = "the script is too large to run";

fn run(s: &mut Session, p: &Value) -> Result<Value> {
    let optional_str = |key: &str| match p.get(key) {
        None => Ok(None),
        Some(Value::String(t)) => Ok(Some(t.as_str())),
        Some(_) => Err(param(format!("`{key}` must be a string"))),
    };
    let (path, source, given_name) = (optional_str("path")?, optional_str("source")?, optional_str("name")?);
    let args = match p.get("args") {
        None => serde_json::Map::new(),
        Some(Value::Object(o)) => o.clone(),
        Some(_) => return Err(param("`args` must be an object")),
    };
    if serde_json::to_vec(&args).map_or(true, |b| b.len() > script::MAX_ARGS_BYTES) {
        return Err(param("`args` is larger than 1 MiB"));
    }
    match p.get("answers") {
        None => {}
        Some(Value::Object(o)) if o.is_empty() => {}
        Some(_) => return Err(param("`answers` must be an empty object: scripts cannot ask questions yet")),
    }
    let fuel = max_fuel(p)?;
    let text = match (path, source) {
        (Some(""), None) => return Err(param("`path` is empty")),
        (Some(path), None) => {
            if path.to_ascii_lowercase().ends_with(".jsxbin") {
                return Err(EngineError::Other(COMPILED.to_string()));
            }
            if !runs(path) {
                return Err(param("`path` must name a .js or .jsx file"));
            }
            // One byte more than a script may have shows that the file is too large.
            let bytes = super::fileio::read_file_head(path, script::MAX_SOURCE_BYTES + 1)?;
            if bytes.len() > script::MAX_SOURCE_BYTES {
                return Err(EngineError::Other(TOO_LARGE.to_string()));
            }
            script_text(&bytes)?
        }
        (None, Some(source)) => {
            if source.len() > script::MAX_SOURCE_BYTES {
                return Err(EngineError::Other(TOO_LARGE.to_string()));
            }
            script_text(source.as_bytes())?
        }
        _ => return Err(param("give exactly one of `path` and `source`")),
    };
    let name = given_name.map(str::to_string).or_else(|| path.map(super::fileio::file_name)).unwrap_or_else(|| "script".to_string());
    s.script_start(script::Request { name: name.clone(), source: text, args, fuel })?;
    if s.script_frames {
        return Ok(json!({"running": true, "name": name}));
    }
    s.script_run_to_end()
}

fn stop(s: &mut Session, _: &Value) -> Result<Value> {
    Ok(json!({"stopped": s.script_request_stop()}))
}

/// The folder a script is in, which its included files are read from.
struct Folder {
    dir: std::path::PathBuf,
    /// The folder with its links followed (none where the file system can't tell).
    real: Option<std::path::PathBuf>,
}

impl Folder {
    /// The folder of the script at `path`.
    fn of(path: &str) -> Self {
        let dir = std::path::Path::new(path).parent().filter(|d| !d.as_os_str().is_empty()).unwrap_or(std::path::Path::new("."));
        Folder { real: std::fs::canonicalize(dir).ok(), dir: dir.to_path_buf() }
    }
}

impl Loader for Folder {
    fn load(&mut self, path: &str, max: usize) -> Loaded {
        let file = self.dir.join(path);
        // A link that leads out of the script's folder isn't followed.
        if let (Some(real), Ok(target)) = (&self.real, std::fs::canonicalize(&file))
            && !target.starts_with(real)
        {
            return Loaded::Refused;
        }
        let file = file.to_string_lossy();
        if crate::file_access::check_read(&file).is_err() {
            return Loaded::Refused;
        }
        super::fileio::read_file_head(&file, max).map_or(Loaded::Missing, Loaded::Bytes)
    }
}

/// The bytes the base64 text `b64` holds, up to `max` and a few more: only the text they take is
/// decoded.
pub(super) fn decode_head(b64: &str, max: usize) -> Option<Vec<u8>> {
    let chars = max.div_ceil(3).saturating_mul(4);
    let mut kept = 0usize;
    let end = b64
        .bytes()
        .position(|b| {
            kept += usize::from(!b.is_ascii_whitespace());
            kept > chars
        })
        .unwrap_or(b64.len());
    vectorcraft_format::base64_decode(b64.get(..end)?)
}

fn check(_: &mut Session, p: &Value) -> Result<Value> {
    const C: &str = "script.check";
    let limits = Limits::default();
    // One byte more than a file may have shows that the file is too large.
    let max = limits.file_bytes.saturating_add(1);
    let path = str_param(p, "path");
    let bytes: std::borrow::Cow<[u8]> = match (path, str_param(p, "data"), str_param(p, "dataBase64")) {
        (Some(path), ..) => super::fileio::read_file_head(path, max)?.into(),
        (None, Some(text), _) => text.as_bytes().get(..max).unwrap_or(text.as_bytes()).into(),
        (None, None, Some(b64)) => decode_head(b64, max).ok_or_else(|| bad(C, "bad dataBase64"))?.into(),
        _ => return Err(bad(C, "give `path`, `data` or `dataBase64`")),
    };
    let name = super::fileio::file_name(str_param(p, "name").or(path).unwrap_or_default());
    // With a path, the file is checked under its own name, which its includes are followed from;
    // `name` names the reply.
    let file = path.map(super::fileio::file_name).unwrap_or_else(|| name.clone());
    let mut folder = path.filter(|_| bool_or(p, "includes", false)).map(Folder::of);
    let report = vectorcraft_scriptcheck::check(&file, &bytes, folder.as_mut().map(|f| f as &mut dyn Loader), &limits);
    Ok(report_json(&name, &report))
}

/// Object `v` with `key: value` added when there is a value.
fn with(mut v: Value, key: &str, value: Option<impl serde::Serialize>) -> Value {
    if let (Some(o), Some(x)) = (v.as_object_mut(), value) {
        o.insert(key.into(), json!(x));
    }
    v
}

/// The reply for report `r` on the script `name`.
fn report_json(name: &str, r: &Report) -> Value {
    let targets: Vec<Value> = r
        .targets
        .iter()
        .map(|t| {
            let v = json!({"value": t.value, "app": t.app, "line": t.line});
            let v = with(v, "instance", t.instance.as_deref());
            let v = with(v, "version", t.version.as_deref());
            let v = with(v, "locale", t.locale.as_deref());
            with(v, "file", t.file.as_deref())
        })
        .collect();
    let directives: Vec<Value> = r
        .directives
        .iter()
        .map(|d| with(json!({"name": d.name, "value": d.value, "line": d.line, "form": d.form}), "file", d.file.as_deref()))
        .collect();
    let includes: Vec<Value> = r
        .includes
        .iter()
        .map(|i| with(with(json!({"value": i.value, "line": i.line, "status": i.status.id()}), "path", i.path.as_deref()), "file", i.file.as_deref()))
        .collect();
    let features: Vec<Value> = r.features.iter().map(|f| json!({"id": f.id, "count": f.count, "lines": f.lines})).collect();
    let members: Vec<Value> = r.members.iter().map(|m| json!({"path": m.name, "count": m.count})).collect();
    let types: Vec<Value> = r.types.iter().map(|t| json!({"name": t.name, "count": t.count})).collect();
    let strings: Vec<Value> = r.menu_strings.iter().map(|s| json!({"value": s.value, "count": s.count, "lines": s.lines})).collect();
    let outside: Vec<Value> = r
        .outside
        .iter()
        .map(|o| with(json!({"id": o.id, "count": o.count, "lines": o.lines}), "modes", Some(&o.modes).filter(|m| !m.is_empty())))
        .collect();
    let problems: Vec<Value> = r
        .problems
        .iter()
        .map(|p| with(with(with(json!({"code": p.code}), "line", p.line), "file", p.file.as_deref()), "detail", p.detail.as_deref()))
        .collect();
    json!({
        "name": name,
        "kind": r.kind.id(),
        "needs": r.needs.iter().map(|n| n.id()).collect::<Vec<_>>(),
        "lines": r.lines,
        "targets": targets,
        "directives": directives,
        "includes": includes,
        "features": features,
        "dom": {"members": members, "types": types},
        "menuCommands": {"strings": strings, "dynamic": r.menu_dynamic},
        "outside": outside,
        "problems": problems,
        "truncated": r.truncated,
    })
}