//! The CLI-side serde front-end for the construction op-script (#157, §C): a
//! JSON op-list document deserializes into the `OpDoc` DTO (so the engine `Op`
//! stays serde-free), which maps 1:1 into `aura_engine::Op`. The `aura graph
//! build` / `aura graph introspect` subcommands here drive these ops through the
//! injected `aura_std::std_vocabulary`.

use std::collections::BTreeMap;

use aura_engine::{blueprint_to_json, replay, BindOpError, GraphSession, Op, OpError, Scalar, ScalarKind};
use aura_std::{std_vocabulary, std_vocabulary_types};
use serde::Deserialize;

/// The wire DTO for one construction op — the document's by-identifier shape,
/// internally tagged by `"op"`, mapped into the serde-free engine `Op`. Bind
/// values are the typed `Scalar` form (`{"I64":2}`); `kind` the capitalized
/// `ScalarKind` form (`"F64"`) — both the #155 representations.
#[derive(Debug, Deserialize)]
#[serde(tag = "op", rename_all = "lowercase")]
enum OpDoc {
    Source { role: String, kind: ScalarKind },
    Input { role: String },
    Add {
        #[serde(rename = "type")]
        type_id: String,
        #[serde(rename = "as", default)]
        as_name: Option<String>,
        #[serde(default)]
        bind: BTreeMap<String, Scalar>,
    },
    Feed { role: String, into: Vec<String> },
    Connect { from: String, to: String },
    Expose {
        from: String,
        #[serde(rename = "as")]
        as_name: String,
    },
}

impl OpDoc {
    /// The op-kind label for the `op N (kind): cause` message.
    fn kind_label(&self) -> &'static str {
        match self {
            OpDoc::Source { .. } => "source",
            OpDoc::Input { .. } => "input",
            OpDoc::Add { .. } => "add",
            OpDoc::Feed { .. } => "feed",
            OpDoc::Connect { .. } => "connect",
            OpDoc::Expose { .. } => "expose",
        }
    }
}

impl From<OpDoc> for Op {
    fn from(d: OpDoc) -> Op {
        match d {
            OpDoc::Source { role, kind } => Op::Source { role, kind },
            OpDoc::Input { role } => Op::Input { role },
            OpDoc::Add { type_id, as_name, bind } => {
                Op::Add { type_id, as_name, bind: bind.into_iter().collect() }
            }
            OpDoc::Feed { role, into } => Op::Feed { role, into },
            OpDoc::Connect { from, to } => Op::Connect { from, to },
            OpDoc::Expose { from, as_name } => Op::Expose { from, as_name },
        }
    }
}

/// Phrase one `OpError` as a human cause (the engine error types are
/// `Display`-free by convention; this is the CLI's presentation layer). The
/// exhaustive match means a new `OpError` variant forces an update here.
fn format_op_error(e: &OpError) -> String {
    match e {
        OpError::UnknownNodeType(t) => format!("unknown node type {t:?}"),
        OpError::DuplicateIdentifier(s) => format!("duplicate identifier {s:?}"),
        OpError::DuplicateOutput(s) => format!("duplicate output name {s:?}"),
        OpError::DuplicateRole(s) => format!("duplicate role {s:?}"),
        OpError::UnknownIdentifier(s) => format!("unknown node identifier {s:?}"),
        OpError::UnknownRole(s) => format!("unknown role {s:?}"),
        OpError::MalformedPort(s) => format!("malformed port reference {s:?}"),
        OpError::UnknownInPort { node, name } => format!("node {node:?} has no input port {name:?}"),
        OpError::AmbiguousInPort { node, name } => format!("node {node:?} has ambiguous input port {name:?}"),
        OpError::UnknownOutPort { node, name } => format!("node {node:?} has no output field {name:?}"),
        OpError::AmbiguousOutPort { node, name } => format!("node {node:?} has ambiguous output field {name:?}"),
        OpError::KindMismatch { from, to, producer, consumer } => {
            format!("kind mismatch {from} -> {to} (producer {producer:?}, consumer {consumer:?})")
        }
        OpError::SlotAlreadyWired { node, slot } => format!("slot {node}.{slot} already wired"),
        OpError::WouldCycle { from, to } => format!("connecting {from} -> {to} would close a cycle"),
        OpError::BadParam { node, err } => match err {
            BindOpError::UnknownParam(p) => format!("node {node} has no param {p:?}"),
            BindOpError::AmbiguousParam(p) => format!("node {node} has ambiguous param {p:?}"),
            BindOpError::KindMismatch { param, expected, got } => {
                format!("param {node}.{param} expects {expected:?} but got {got:?}")
            }
        },
        OpError::UnconnectedPort { node, slot } => format!("slot {node}.{slot} is unconnected"),
        OpError::RoleKindMismatch { role } => format!("input role {role} fans into slots of differing kinds"),
        OpError::UnboundRootRole { role } => format!("root input role {role} is unbound"),
        OpError::Incomplete(ce) => format!("{ce:?}"),
    }
}

/// Parse a JSON op-list document, replay it through `std_vocabulary`, and return
/// the emitted #155 blueprint JSON — or a `op N (kind): cause` message (a per-op
/// fault, attributed by the retained op-kind list) / `finalize: cause` (a
/// holistic fault past the last op).
pub fn build_from_str(doc: &str) -> Result<String, String> {
    let docs: Vec<OpDoc> = serde_json::from_str(doc).map_err(|e| format!("invalid op-list: {e}"))?;
    let labels: Vec<&'static str> = docs.iter().map(OpDoc::kind_label).collect();
    let ops: Vec<Op> = docs.into_iter().map(Op::from).collect();
    match replay("graph", ops, &std_vocabulary) {
        Ok(composite) => blueprint_to_json(&composite).map_err(|e| format!("serialize error: {e:?}")),
        Err((idx, err)) => {
            let cause = format_op_error(&err);
            match labels.get(idx) {
                Some(kind) => Err(format!("op {idx} ({kind}): {cause}")),
                None => Err(format!("finalize: {cause}")),
            }
        }
    }
}

/// `aura graph build`: read the op-list document from stdin, build, and print the
/// blueprint to stdout — or the cause to stderr and exit non-zero.
pub fn build_cmd() {
    use std::io::Read;
    let mut doc = String::new();
    if let Err(e) = std::io::stdin().read_to_string(&mut doc) {
        eprintln!("aura: reading stdin: {e}");
        std::process::exit(2);
    }
    match build_from_str(&doc) {
        Ok(json) => println!("{json}"),
        Err(msg) => {
            eprintln!("aura: {msg}");
            std::process::exit(2);
        }
    }
}

/// `aura graph introspect --node <T>`: a type's ports + kinds + param paths,
/// read off the pre-build schema (no graph built). `Err` if `T` is not in the
/// closed vocabulary.
pub fn introspect_node(type_id: &str) -> Result<String, String> {
    let builder = std_vocabulary(type_id).ok_or_else(|| format!("unknown node type {type_id:?}"))?;
    let schema = builder.schema();
    let mut out = format!("{}\n", builder.label());
    for port in &schema.inputs {
        out.push_str(&format!("  in   {}:{:?}\n", port.name, port.kind));
    }
    for field in &schema.output {
        out.push_str(&format!("  out  {}:{:?}\n", field.name, field.kind));
    }
    for p in builder.params() {
        out.push_str(&format!("  param {}:{:?}  (bind {{\"{:?}\": <v>}})\n", p.name, p.kind, p.kind));
    }
    Ok(out)
}

/// `aura graph introspect --unwired`: the still-open interior slots of a partial
/// op-list document, by-identifier (applies the ops, does NOT finalize).
pub fn introspect_unwired(doc: &str) -> Result<String, String> {
    let docs: Vec<OpDoc> = serde_json::from_str(doc).map_err(|e| format!("invalid op-list: {e}"))?;
    let mut session = GraphSession::new("introspect", &std_vocabulary);
    for (i, d) in docs.into_iter().enumerate() {
        session.apply(Op::from(d)).map_err(|e| format!("op {i}: {}", format_op_error(&e)))?;
    }
    let mut out = String::new();
    for (slot, kind) in session.unwired() {
        out.push_str(&format!("{slot}:{kind:?}\n"));
    }
    Ok(out)
}

/// `aura graph introspect`: dispatch the three read-only queries.
pub fn introspect_cmd(rest: &[&str]) {
    match rest {
        ["--vocabulary"] => {
            for t in std_vocabulary_types() {
                println!("{t}");
            }
        }
        ["--node", type_id] => match introspect_node(type_id) {
            Ok(s) => print!("{s}"),
            Err(m) => {
                eprintln!("aura: {m}");
                std::process::exit(2);
            }
        },
        ["--unwired"] => {
            use std::io::Read;
            let mut doc = String::new();
            if let Err(e) = std::io::stdin().read_to_string(&mut doc) {
                eprintln!("aura: reading stdin: {e}");
                std::process::exit(2);
            }
            match introspect_unwired(&doc) {
                Ok(s) => print!("{s}"),
                Err(m) => {
                    eprintln!("aura: {m}");
                    std::process::exit(2);
                }
            }
        }
        _ => {
            eprintln!("aura: usage: aura graph introspect --vocabulary | --node <T> | --unwired");
            std::process::exit(2);
        }
    }
}

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

    /// The spec's worked-example document deserializes into the op vocabulary and
    /// maps into engine `Op`s that replay into a compilable signal blueprint —
    /// the DTO is a faithful front-end over the engine surface.
    #[test]
    fn opdoc_document_deserializes_and_replays() {
        let doc = r#"[
            {"op":"source","role":"price","kind":"F64"},
            {"op":"add","type":"SMA","as":"fast","bind":{"length":{"I64":2}}},
            {"op":"add","type":"SMA","as":"slow","bind":{"length":{"I64":4}}},
            {"op":"add","type":"Sub"},
            {"op":"add","type":"Bias"},
            {"op":"feed","role":"price","into":["fast.series","slow.series"]},
            {"op":"connect","from":"fast.value","to":"sub.lhs"},
            {"op":"connect","from":"slow.value","to":"sub.rhs"},
            {"op":"connect","from":"sub.value","to":"bias.signal"},
            {"op":"expose","from":"bias.bias","as":"bias"}
        ]"#;
        let docs: Vec<OpDoc> = serde_json::from_str(doc).expect("document parses");
        assert_eq!(docs.len(), 10);
        assert_eq!(docs[1].kind_label(), "add");
        let ops: Vec<Op> = docs.into_iter().map(Op::from).collect();
        // both SMA lengths are bound, so the only open param is bias.scale (f64).
        let composite = replay("graph", ops, &std_vocabulary).expect("replay resolves");
        composite.compile_with_params(&[Scalar::f64(0.5)]).expect("compiles");
    }

    #[test]
    fn build_from_str_emits_blueprint_json_for_valid_document() {
        let doc = r#"[
            {"op":"source","role":"price","kind":"F64"},
            {"op":"add","type":"SMA","as":"fast","bind":{"length":{"I64":2}}},
            {"op":"add","type":"SMA","as":"slow","bind":{"length":{"I64":4}}},
            {"op":"add","type":"Sub"},
            {"op":"add","type":"Bias"},
            {"op":"feed","role":"price","into":["fast.series","slow.series"]},
            {"op":"connect","from":"fast.value","to":"sub.lhs"},
            {"op":"connect","from":"slow.value","to":"sub.rhs"},
            {"op":"connect","from":"sub.value","to":"bias.signal"},
            {"op":"expose","from":"bias.bias","as":"bias"}
        ]"#;
        let json = super::build_from_str(doc).expect("valid document builds");
        assert!(json.contains("\"format_version\":1"), "emits the #155 envelope: {json}");
        assert!(json.contains("\"SMA\""), "carries the SMA nodes: {json}");
    }

    #[test]
    fn build_from_str_reports_unknown_node_at_its_op_index() {
        let doc = r#"[{"op":"add","type":"SMA","as":"fast"},{"op":"add","type":"Nope"}]"#;
        let err = super::build_from_str(doc).unwrap_err();
        assert_eq!(err, "op 1 (add): unknown node type \"Nope\"");
    }

    #[test]
    fn build_from_str_reports_unconnected_slot_at_finalize() {
        // sub.rhs left unwired -> the holistic 0-arm fires at the finalize step.
        let doc = r#"[
            {"op":"source","role":"price","kind":"F64"},
            {"op":"add","type":"SMA","as":"fast"},
            {"op":"add","type":"SMA","as":"slow"},
            {"op":"add","type":"Sub"},
            {"op":"feed","role":"price","into":["fast.series","slow.series"]},
            {"op":"connect","from":"fast.value","to":"sub.lhs"}
        ]"#;
        let err = super::build_from_str(doc).unwrap_err();
        assert!(err.starts_with("finalize: "), "finalize fault, got: {err}");
        assert!(err.contains("sub.rhs") && err.contains("is unconnected"),
            "names the unconnected slot by-identifier, got: {err}");
        assert!(!err.contains("node:"), "no raw machine index in the message, got: {err}");
    }

    #[test]
    fn introspect_node_lists_ports_kinds_and_params() {
        let out = super::introspect_node("SMA").expect("SMA is in the vocabulary");
        assert!(out.contains("series"), "lists the input port: {out}");
        assert!(out.contains("value"), "lists the output field: {out}");
        assert!(out.contains("length"), "lists the param path: {out}");
        assert!(super::introspect_node("Nope").is_err(), "rejects an unknown type");
    }

    /// A bind whose value-kind mismatches the param reads as prose, like the connect
    /// mismatch — not a Debug struct.
    #[test]
    fn build_from_str_bad_bind_kind_reads_as_prose() {
        let doc = r#"[{"op":"add","type":"SMA","as":"fast","bind":{"length":{"F64":2.0}}}]"#;
        let err = super::build_from_str(doc).unwrap_err();
        assert_eq!(err, "op 0 (add): param fast.length expects I64 but got F64");
    }

    /// A bind to a param the node does not declare reads as prose naming the node
    /// and the unknown param — not a Debug struct.
    #[test]
    fn build_from_str_unknown_bind_param_reads_as_prose() {
        let doc = r#"[{"op":"add","type":"SMA","as":"fast","bind":{"window":{"I64":2}}}]"#;
        let err = super::build_from_str(doc).unwrap_err();
        assert_eq!(err, "op 0 (add): node fast has no param \"window\"");
    }

    /// The ambiguous-param branch of the bind-error presenter is phrased as prose
    /// naming the node and the ambiguous param. No std primitive carries two
    /// same-named params, so the branch is unreachable end-to-end and is pinned on
    /// the presenter directly.
    #[test]
    fn ambiguous_bind_param_reads_as_prose() {
        let msg = format_op_error(&OpError::BadParam {
            node: "fast".to_string(),
            err: BindOpError::AmbiguousParam("length".to_string()),
        });
        assert_eq!(msg, "node fast has ambiguous param \"length\"");
    }

    /// `introspect --node` shows the typed-Scalar bind-value form so a hand-author
    /// does not have to read source to learn the `{"I64": <v>}` wrapping.
    #[test]
    fn introspect_node_shows_the_bind_form() {
        let out = super::introspect_node("SMA").expect("SMA is in the vocabulary");
        assert!(out.contains("(bind {\"I64\": <v>})"), "shows the bind-value form: {out}");
    }

    #[test]
    fn introspect_unwired_reports_open_slots_of_a_partial_document() {
        let doc = r#"[
            {"op":"add","type":"SMA","as":"fast"},
            {"op":"add","type":"Sub"},
            {"op":"connect","from":"fast.value","to":"sub.lhs"}
        ]"#;
        let out = super::introspect_unwired(doc).expect("partial document introspects");
        assert!(out.contains("sub.rhs"), "sub.rhs is still open: {out}");
        assert!(out.contains("fast.series"), "fast.series is still open: {out}");
        assert!(!out.contains("sub.lhs"), "sub.lhs is covered: {out}");
    }
}