dsp_cli/render/

json.rs

//! JSON renderer — newline-delimited JSON output.
//!
//! Every response is a single object with `_meta` first, plus exactly one of
//! `data` (success) or `error` (failure):
//!
//! ```json
//! {"_meta": {"server": "…", "auth": "…", "exit_code": 0}, "data": { … }}
//! {"_meta": {"server": "…", "auth": "…", "exit_code": 3}, "error": {"kind": "…", "message": "…"}}
//! ```
//!
//! `data` is an object for single-result commands and an array for list
//! commands (Phase 4+). The shape is uniform across every command so a
//! consumer always parses one object from stdout: if `.error` is present it
//! failed, otherwise read `.data`. The `server` lives only in `_meta` — it is
//! not repeated inside `data`. Key order is deterministic (serde_json
//! `preserve_order`); `_meta` is always first. See ADR-0003 and ADR-0012.

use std::io::{self, Write};

use serde_json::json;

use crate::diagnostic::Diagnostic;
use crate::model::{
    DataModelDetail, DataModelStructure, DatePoint, ProjectDetail, ResourceDetail, ValueContent,
};
use crate::render::auth::{
    AuthLoginOutcome, AuthLogoutOutcome, AuthSetTokenOutcome, AuthStatusOutcome,
};
use crate::render::dump::{DumpDeleteOutcome, DumpOutcome};
use crate::render::{
    DataModelListView, MetaContext, ProjectListView, Renderer, ResourceListPagination,
    ResourceListView, ResourceTypeListView,
};

/// Renders output as newline-delimited JSON.
pub struct JsonRenderer {
    out: Box<dyn Write>,
}

impl JsonRenderer {
    /// Creates a renderer writing to stdout.
    pub fn new() -> Self {
        Self {
            out: Box::new(io::stdout()),
        }
    }

    /// Creates a renderer writing to an arbitrary `Write` sink (used in tests).
    pub fn with_writer(w: impl Write + 'static) -> Self {
        Self { out: Box::new(w) }
    }
}

impl Default for JsonRenderer {
    fn default() -> Self {
        Self::new()
    }
}

/// Build the `_meta` block common to every JSON output object.
fn meta_block(meta: &MetaContext, exit_code: u8) -> serde_json::Value {
    json!({
        "server": meta.server_label,
        "auth": meta.auth_state,
        "exit_code": exit_code,
    })
}

/// Build a JSON value object for a single `ValueContent` (per ADR-0013 matrix).
///
/// Key order is deterministic: `value_type` is always first, then type-specific
/// keys in the order specified by the matrix. Raw server values are kept verbatim
/// (no sanitisation — ADR-0003 fidelity; sanitisation is prose-only per D7).
fn value_content_to_json(vc: &ValueContent) -> serde_json::Value {
    use serde_json::Map;
    let mut m = Map::new();
    match vc {
        ValueContent::Text(s) => {
            m.insert(
                "value_type".into(),
                serde_json::Value::String("text".into()),
            );
            m.insert("text".into(), serde_json::Value::String(s.clone()));
        }
        ValueContent::Integer(n) => {
            m.insert(
                "value_type".into(),
                serde_json::Value::String("integer".into()),
            );
            m.insert("value".into(), serde_json::Value::Number((*n).into()));
        }
        ValueContent::Decimal(s) => {
            m.insert(
                "value_type".into(),
                serde_json::Value::String("decimal".into()),
            );
            m.insert("value".into(), serde_json::Value::String(s.clone()));
        }
        ValueContent::Boolean(b) => {
            m.insert(
                "value_type".into(),
                serde_json::Value::String("boolean".into()),
            );
            m.insert("value".into(), serde_json::Value::Bool(*b));
        }
        ValueContent::Date(dv) => {
            m.insert(
                "value_type".into(),
                serde_json::Value::String("date".into()),
            );
            m.insert(
                "calendar".into(),
                serde_json::Value::String(dv.calendar.clone()),
            );
            // Build start/end point objects — omit absent sub-fields (null for era when None).
            let point_to_json = |p: &DatePoint| {
                json!({
                    "year": p.year,
                    "month": p.month,
                    "day": p.day,
                    "era": p.era,
                })
            };
            m.insert("start".into(), point_to_json(&dv.start));
            m.insert("end".into(), point_to_json(&dv.end));
        }
        ValueContent::Time(s) => {
            m.insert(
                "value_type".into(),
                serde_json::Value::String("time".into()),
            );
            m.insert("value".into(), serde_json::Value::String(s.clone()));
        }
        ValueContent::Uri(s) => {
            m.insert("value_type".into(), serde_json::Value::String("uri".into()));
            m.insert("value".into(), serde_json::Value::String(s.clone()));
        }
        ValueContent::Color(s) => {
            m.insert(
                "value_type".into(),
                serde_json::Value::String("color".into()),
            );
            m.insert("value".into(), serde_json::Value::String(s.clone()));
        }
        ValueContent::Geoname(s) => {
            m.insert(
                "value_type".into(),
                serde_json::Value::String("geoname".into()),
            );
            m.insert("value".into(), serde_json::Value::String(s.clone()));
        }
        ValueContent::ListItem { node_iri, label } => {
            m.insert(
                "value_type".into(),
                serde_json::Value::String("list-item".into()),
            );
            m.insert(
                "node_iri".into(),
                serde_json::Value::String(node_iri.clone()),
            );
            let label_val = match label {
                Some(s) => serde_json::Value::String(s.clone()),
                None => serde_json::Value::Null,
            };
            m.insert("label".into(), label_val);
        }
        ValueContent::Link {
            target_iri,
            target_label,
        } => {
            m.insert(
                "value_type".into(),
                serde_json::Value::String("link".into()),
            );
            m.insert(
                "target_iri".into(),
                serde_json::Value::String(target_iri.clone()),
            );
            let tl_val = match target_label {
                Some(s) => serde_json::Value::String(s.clone()),
                None => serde_json::Value::Null,
            };
            m.insert("target_label".into(), tl_val);
        }
        ValueContent::File(fv) => {
            use crate::model::resource_type::ValueType;
            let type_token = fv.value_type.as_token().to_string();
            m.insert("value_type".into(), serde_json::Value::String(type_token));
            m.insert(
                "filename".into(),
                serde_json::Value::String(fv.filename.clone()),
            );
            m.insert("url".into(), serde_json::Value::String(fv.url.clone()));
            // width/height: only meaningful for still-image, null for others.
            match fv.value_type {
                ValueType::StillImage => {
                    let w_val: serde_json::Value = fv.width.map_or(serde_json::Value::Null, |w| {
                        serde_json::Value::Number(w.into())
                    });
                    let h_val: serde_json::Value = fv.height.map_or(serde_json::Value::Null, |h| {
                        serde_json::Value::Number(h.into())
                    });
                    m.insert("width".into(), w_val);
                    m.insert("height".into(), h_val);
                }
                _ => {
                    m.insert("width".into(), serde_json::Value::Null);
                    m.insert("height".into(), serde_json::Value::Null);
                }
            }
        }
        ValueContent::Raw { value_type, text } => {
            m.insert(
                "value_type".into(),
                serde_json::Value::String(value_type.clone()),
            );
            m.insert("text".into(), serde_json::Value::String(text.clone()));
        }
    }
    serde_json::Value::Object(m)
}

/// Map a `Diagnostic` variant to its stable JSON `kind` string (per ADR-0012).
fn diagnostic_kind(diag: &Diagnostic) -> &'static str {
    match diag {
        Diagnostic::Usage(_) => "usage",
        Diagnostic::AuthRequired(_) => "auth_required",
        Diagnostic::NotFound(_) => "not_found",
        Diagnostic::ServerError(_) => "server_error",
        Diagnostic::Network(_) => "network",
        Diagnostic::Conflict(_) => "conflict",
        Diagnostic::Io(_) => "io",
        Diagnostic::Internal(_) | Diagnostic::NotImplemented(_) => "internal",
    }
}

impl Renderer for JsonRenderer {
    fn diagnostic(&mut self, diag: &Diagnostic, meta: &MetaContext) -> Result<(), Diagnostic> {
        // JSON errors emit the full ADR-0012 error envelope to stdout so a JSON
        // consumer has a single stream to parse (not stdout + stderr).
        let exit_code = diag.exit_category() as u8;
        let obj = json!({
            "_meta": meta_block(meta, exit_code),
            "error": {
                "kind": diagnostic_kind(diag),
                "message": diag.to_string(),
            },
        });
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }

    fn auth_login(
        &mut self,
        outcome: &AuthLoginOutcome,
        meta: &MetaContext,
    ) -> Result<(), Diagnostic> {
        let obj = json!({
            "_meta": meta_block(meta, 0),
            "data": {
                "user": outcome.user,
                "expires_at": outcome.expires_at.map(|dt| dt.to_rfc3339()),
                "state": "login_success",
            },
        });
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }

    fn auth_status(
        &mut self,
        outcome: &AuthStatusOutcome,
        meta: &MetaContext,
    ) -> Result<(), Diagnostic> {
        let obj = match outcome {
            AuthStatusOutcome::LoggedIn {
                server: _,
                user,
                expires_at,
                expired,
            } => json!({
                "_meta": meta_block(meta, 0),
                "data": {
                    "user": user,
                    "expires_at": expires_at.map(|dt| dt.to_rfc3339()),
                    "state": if *expired { "expired" } else { "logged_in" },
                },
            }),
            // DSP_TOKEN env-override: data shape is uniform with the LoggedIn case
            // (user: null, expires_at: rfc3339 or null, state: "logged_in"|"expired").
            // The "via DSP_TOKEN" disclosure is carried by _meta.auth, not by a
            // source key in data, to keep the data shape stable across all three outcomes.
            AuthStatusOutcome::AuthenticatedViaEnv {
                server: _,
                expires_at,
                expired,
            } => json!({
                "_meta": meta_block(meta, 0),
                "data": {
                    "user": null,
                    "expires_at": expires_at.map(|dt| dt.to_rfc3339()),
                    "state": if *expired { "expired" } else { "logged_in" },
                },
            }),
            AuthStatusOutcome::NotLoggedIn { server: _ } => json!({
                "_meta": meta_block(meta, 0),
                "data": {
                    "user": null,
                    "expires_at": null,
                    "state": "not_logged_in",
                },
            }),
        };
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }

    fn auth_logout(
        &mut self,
        outcome: &AuthLogoutOutcome,
        meta: &MetaContext,
    ) -> Result<(), Diagnostic> {
        let obj = json!({
            "_meta": meta_block(meta, 0),
            "data": {
                "was_cached": outcome.was_cached,
                "state": if outcome.was_cached { "logout_was_cached" } else { "logout_no_op" },
            },
        });
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }

    fn auth_set_token(
        &mut self,
        outcome: &AuthSetTokenOutcome,
        meta: &MetaContext,
    ) -> Result<(), Diagnostic> {
        let obj = json!({
            "_meta": meta_block(meta, 0),
            "data": {
                "user": outcome.user,
                "expires_at": outcome.expires_at.map(|dt| dt.to_rfc3339()),
                "state": "token_cached",
            },
        });
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }

    fn project_dump(
        &mut self,
        outcome: &DumpOutcome,
        meta: &MetaContext,
    ) -> Result<(), Diagnostic> {
        let obj = json!({
            "_meta": meta_block(meta, 0),
            "data": {
                "path": outcome.path.display().to_string(),
                "bytes": outcome.bytes,
                "cleaned_up": outcome.cleaned_up,
                "reused": outcome.reused,
                "created_at": outcome.created_at.map(|dt| dt.to_rfc3339()),
            },
        });
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }

    fn project_dump_deleted(
        &mut self,
        outcome: &DumpDeleteOutcome,
        meta: &MetaContext,
    ) -> Result<(), Diagnostic> {
        let obj = if let Some(ref note) = outcome.note {
            json!({
                "_meta": meta_block(meta, 0),
                "data": {
                    "deleted": outcome.deleted,
                    "note": note,
                },
            })
        } else {
            json!({
                "_meta": meta_block(meta, 0),
                "data": {
                    "deleted": outcome.deleted,
                },
            })
        };
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }

    fn projects(&mut self, view: &ProjectListView, meta: &MetaContext) -> Result<(), Diagnostic> {
        // Build data array. Each element uses `json!` with insertion-order keys
        // (preserve_order feature on serde_json, per ADR-0003).
        // longname None → JSON null.
        let data: Vec<serde_json::Value> = view
            .items
            .iter()
            .map(|item| {
                json!({
                    "iri": item.iri,
                    "shortcode": item.shortcode,
                    "shortname": item.shortname,
                    "longname": item.longname,
                    "status": item.status.as_str(),
                    "data_models": item.data_models,
                })
            })
            .collect();

        let obj = json!({
            "_meta": meta_block(meta, 0),
            "data": data,
        });
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }

    fn project_describe(
        &mut self,
        project: &ProjectDetail,
        meta: &MetaContext,
    ) -> Result<(), Diagnostic> {
        // `data` is a single object (ADR-0003). Deterministic key order via `json!`
        // (preserve_order feature ensures insertion order).
        let description: Vec<serde_json::Value> = project
            .description
            .iter()
            .map(|d| {
                json!({
                    "value": d.value,
                    "language": d.language,
                })
            })
            .collect();

        let data_models: Vec<serde_json::Value> = project
            .data_models
            .iter()
            .map(|dm| {
                json!({
                    "name": dm.name,
                    "iri": dm.iri,
                })
            })
            .collect();

        let obj = json!({
            "_meta": meta_block(meta, 0),
            "data": {
                "iri": project.iri,
                "shortcode": project.shortcode,
                "shortname": project.shortname,
                "longname": project.longname,
                "status": project.status.as_str(),
                "description": description,
                "keywords": project.keywords,
                "data_models": data_models,
            },
        });
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }

    fn data_model_describe(
        &mut self,
        detail: &DataModelDetail,
        meta: &MetaContext,
    ) -> Result<(), Diagnostic> {
        // ADR-0003 single-object envelope. `last_modified` is the full RFC3339
        // string (lossless). `resource_types` is an array of per-resource-type
        // objects (name, iri, label).
        let resource_types: Vec<serde_json::Value> = detail
            .resource_types
            .iter()
            .map(|rt| {
                json!({
                    "name": rt.name,
                    "iri": rt.iri,
                    "label": rt.label,
                })
            })
            .collect();

        let obj = json!({
            "_meta": meta_block(meta, 0),
            "data": {
                "name": detail.name,
                "iri": detail.iri,
                "label": detail.label,
                "last_modified": detail.last_modified,
                "resource_types": resource_types,
            },
        });
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }

    fn data_models(
        &mut self,
        view: &DataModelListView,
        meta: &MetaContext,
    ) -> Result<(), Diagnostic> {
        // Build data array — per-item key order via `json!` insertion order
        // (preserve_order feature on serde_json, per ADR-0003).
        // label None → JSON null; last_modified None → JSON null; is_builtin → bool.
        let data: Vec<serde_json::Value> = view
            .items
            .iter()
            .map(|item| {
                json!({
                    "name": item.name,
                    "iri": item.iri,
                    "label": item.label,
                    "last_modified": item.last_modified,
                    "is_builtin": item.is_builtin,
                })
            })
            .collect();

        let obj = json!({
            "_meta": meta_block(meta, 0),
            "data": data,
        });
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }

    fn resource_types(
        &mut self,
        view: &ResourceTypeListView,
        meta: &MetaContext,
    ) -> Result<(), Diagnostic> {
        // Build data array — per-item key order via `json!` insertion order
        // (preserve_order feature on serde_json, per ADR-0003).
        // label None → JSON null; is_builtin → bool.
        let data: Vec<serde_json::Value> = view
            .items
            .iter()
            .map(|item| {
                json!({
                    "name": item.name,
                    "iri": item.iri,
                    "label": item.label,
                    "is_builtin": item.is_builtin,
                })
            })
            .collect();

        let obj = json!({
            "_meta": meta_block(meta, 0),
            "data": data,
        });
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }

    fn resource_type_describe(
        &mut self,
        detail: &crate::model::ResourceTypeDetail,
        meta: &MetaContext,
    ) -> Result<(), Diagnostic> {
        // ADR-0003 single-object envelope. `_meta` first, `data` is the resource-type
        // object. Fields array carries one object per field (name, iri, label,
        // value_type, link_target, cardinality, is_builtin, data_model).
        let fields: Vec<serde_json::Value> = detail
            .fields
            .iter()
            .map(|f| {
                json!({
                    "name": f.name,
                    "iri": f.iri,
                    "label": f.label,
                    "value_type": f.value_type.to_string(),
                    "link_target": f.link_target,
                    "cardinality": f.cardinality.to_string(),
                    "is_builtin": f.is_builtin,
                    "data_model": f.data_model,
                })
            })
            .collect();

        let obj = json!({
            "_meta": meta_block(meta, 0),
            "data": {
                "name": detail.name,
                "iri": detail.iri,
                "label": detail.label,
                "data_model": detail.data_model,
                "representation": detail.representation.as_ref().map(|r| r.to_string()),
                "super_types": detail.super_types,
                "fields": fields,
            },
        });
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }

    fn data_model_structure(
        &mut self,
        structure: &DataModelStructure,
        meta: &MetaContext,
    ) -> Result<(), Diagnostic> {
        // ADR-0003 flat-array envelope. Each element carries all 5 keys (none omitted).
        // Optional values are emitted as JSON null (matching resource_type_describe lines
        // 476-485 which render None Options as null — never skip_serializing_if).
        let data: Vec<serde_json::Value> = structure
            .relations
            .iter()
            .map(|r| {
                json!({
                    "source": r.source,
                    "target": r.target,
                    "kind": r.kind.to_string(),
                    "field": r.field,
                    "target_data_model": r.target_data_model,
                })
            })
            .collect();

        let obj = json!({
            "_meta": meta_block(meta, 0),
            "data": data,
        });
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }

    fn resources(&mut self, view: &ResourceListView, meta: &MetaContext) -> Result<(), Diagnostic> {
        // Build data array.
        let data: Vec<serde_json::Value> = view
            .items
            .iter()
            .map(|item| {
                json!({
                    "label": item.label,
                    "iri": item.iri,
                    "ark_url": item.ark_url,
                    "creation_date": item.creation_date,
                    "last_modified": item.last_modified,
                    "resource_type": item.resource_type,
                })
            })
            .collect();

        // Build _meta pagination keys (D5 — two asymmetric shapes by mode).
        let mut meta_obj = meta_block(meta, 0);
        match &view.pagination {
            ResourceListPagination::SinglePage {
                page,
                may_have_more,
            } => {
                meta_obj["page"] = serde_json::Value::from(*page);
                meta_obj["may_have_more_results"] = serde_json::Value::from(*may_have_more);
            }
            ResourceListPagination::AllPages { pages_fetched } => {
                meta_obj["pages_fetched"] = serde_json::Value::from(*pages_fetched);
                // AllPages always exits on may_have_more_results = false (loop invariant).
                meta_obj["may_have_more_results"] = serde_json::Value::from(false);
            }
        }

        // D3: add `note` to _meta when filter_warning is Some.
        if let Some(ref fw) = meta.filter_warning {
            meta_obj["note"] = serde_json::Value::from(fw.as_str());
        }

        let obj = json!({
            "_meta": meta_obj,
            "data": data,
        });
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }

    fn resource_describe(
        &mut self,
        detail: &ResourceDetail,
        meta: &MetaContext,
    ) -> Result<(), Diagnostic> {
        // ADR-0003 single-object envelope. `data` is an object (not array).
        // Keys in deterministic order; `None` → JSON null.
        // D3: add `note` to _meta when filter_warning is Some.
        let mut meta_obj = meta_block(meta, 0);
        if let Some(ref fw) = meta.filter_warning {
            meta_obj["note"] = serde_json::Value::from(fw.as_str());
        }

        // Build data object with explicit key ordering (preserve_order, ADR-0003).
        let mut data = serde_json::Map::new();
        data.insert(
            "label".into(),
            serde_json::Value::String(detail.label.clone()),
        );
        data.insert("iri".into(), serde_json::Value::String(detail.iri.clone()));
        data.insert(
            "resource_type".into(),
            serde_json::Value::String(detail.resource_type.clone()),
        );
        data.insert(
            "ark_url".into(),
            detail
                .ark_url
                .as_ref()
                .map_or(serde_json::Value::Null, |s| {
                    serde_json::Value::String(s.clone())
                }),
        );
        data.insert(
            "creation_date".into(),
            detail
                .creation_date
                .as_ref()
                .map_or(serde_json::Value::Null, |s| {
                    serde_json::Value::String(s.clone())
                }),
        );
        data.insert(
            "last_modified".into(),
            detail
                .last_modified
                .as_ref()
                .map_or(serde_json::Value::Null, |s| {
                    serde_json::Value::String(s.clone())
                }),
        );
        data.insert(
            "attached_project".into(),
            detail
                .attached_project
                .as_ref()
                .map_or(serde_json::Value::Null, |s| {
                    serde_json::Value::String(s.clone())
                }),
        );
        data.insert(
            "owner".into(),
            detail.owner.as_ref().map_or(serde_json::Value::Null, |s| {
                serde_json::Value::String(s.clone())
            }),
        );
        data.insert(
            "visibility".into(),
            detail
                .visibility
                .as_ref()
                .map_or(serde_json::Value::Null, |v| {
                    serde_json::Value::String(v.as_str().into())
                }),
        );
        data.insert(
            "your_access".into(),
            detail
                .your_access
                .as_ref()
                .map_or(serde_json::Value::Null, |a| {
                    serde_json::Value::String(a.as_str().into())
                }),
        );
        // `values` key is present only when --values was set (detail.values is Some).
        // Absent (not null) when None — preserves 8b envelope byte-for-byte.
        if let Some(ref fields) = detail.values {
            let values_arr: Vec<serde_json::Value> = fields
                .iter()
                .map(|fv| {
                    let value_objs: Vec<serde_json::Value> = fv
                        .values
                        .iter()
                        .map(|v| {
                            let mut obj = value_content_to_json(&v.content);
                            if let (Some(c), serde_json::Value::Object(m)) = (&v.comment, &mut obj)
                            {
                                m.insert("comment".into(), serde_json::Value::String(c.clone()));
                            }
                            obj
                        })
                        .collect();
                    let mut fg = serde_json::Map::new();
                    fg.insert("field".into(), serde_json::Value::String(fv.name.clone()));
                    let fl_val = match &fv.label {
                        Some(s) => serde_json::Value::String(s.clone()),
                        None => serde_json::Value::Null,
                    };
                    fg.insert("field_label".into(), fl_val);
                    fg.insert("values".into(), serde_json::Value::Array(value_objs));
                    serde_json::Value::Object(fg)
                })
                .collect();
            data.insert("values".into(), serde_json::Value::Array(values_arr));
        }

        let obj = json!({
            "_meta": meta_obj,
            "data": serde_json::Value::Object(data),
        });
        writeln!(
            self.out,
            "{}",
            serde_json::to_string(&obj)
                .map_err(|e| Diagnostic::Internal(format!("json serialisation error: {e}")))?
        )?;
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::model::{
        DataModel, DataModelDetail, DataModelSummary, Project, ProjectDescription, ProjectDetail,
        ProjectStatus, ResourceType, ResourceTypeSummary,
    };
    use crate::render::test_support::{SharedBuf, make_meta};
    use crate::render::{DataModelListView, ResourceTypeListView};

    #[test]
    fn projects_json_output() {
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let items = vec![
            Project {
                iri: "http://rdfh.ch/projects/0001".into(),
                shortcode: "0001".into(),
                shortname: "anything".into(),
                longname: Some("Anything Project".into()),
                status: ProjectStatus::Active,
                data_models: 2,
            },
            Project {
                iri: "http://rdfh.ch/projects/0002".into(),
                shortcode: "0002".into(),
                shortname: "images".into(),
                longname: None,
                status: ProjectStatus::Inactive,
                data_models: 0,
            },
        ];
        let view = ProjectListView {
            items,
            total: 2,
            filter: None,
        };
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.projects(&view, &meta).unwrap();

        let s = out.string();
        let parsed: serde_json::Value = serde_json::from_str(s.trim()).unwrap();

        // _meta present
        assert_eq!(parsed["_meta"]["auth"], "anonymous");
        assert_eq!(parsed["_meta"]["server"], "https://api.test.dasch.swiss");
        assert_eq!(parsed["_meta"]["exit_code"], 0);

        // data is array
        let data = parsed["data"].as_array().unwrap();
        assert_eq!(data.len(), 2);

        // first item
        assert_eq!(data[0]["shortcode"], "0001");
        assert_eq!(data[0]["shortname"], "anything");
        assert_eq!(data[0]["longname"], "Anything Project");
        assert_eq!(data[0]["status"], "active");
        assert_eq!(data[0]["data_models"], 2);
        assert_eq!(data[0]["iri"], "http://rdfh.ch/projects/0001");

        // second item — longname None → null
        assert_eq!(data[1]["shortcode"], "0002");
        assert!(data[1]["longname"].is_null());
        assert_eq!(data[1]["status"], "inactive");
        assert_eq!(data[1]["data_models"], 0);
    }

    #[test]
    fn projects_json_empty_data_array() {
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let view = ProjectListView {
            items: vec![],
            total: 0,
            filter: None,
        };
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.projects(&view, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        assert!(parsed["data"].as_array().unwrap().is_empty());
    }

    /// Assert that `diagnostic_kind` returns the correct stable string for every
    /// `Diagnostic` variant. This test is intentionally exhaustive: adding a new
    /// variant without a corresponding arm in `diagnostic_kind` will cause a
    /// compiler warning (non-exhaustive match) at the match site, but this test
    /// ensures the mapping is also exercised at the call level so the kind string
    /// is verified, not just the pattern.
    #[test]
    fn diagnostic_kind_covers_all_variants() {
        let cases: &[(&Diagnostic, &str)] = &[
            (&Diagnostic::Usage("x".into()), "usage"),
            (&Diagnostic::AuthRequired("x".into()), "auth_required"),
            (&Diagnostic::NotFound("x".into()), "not_found"),
            (&Diagnostic::ServerError("x".into()), "server_error"),
            (&Diagnostic::Network("x".into()), "network"),
            (&Diagnostic::Conflict("x".into()), "conflict"),
            (&Diagnostic::Io("x".into()), "io"),
            (&Diagnostic::Internal("x".into()), "internal"),
            (&Diagnostic::NotImplemented("x".into()), "internal"),
        ];
        for (diag, expected_kind) in cases {
            assert_eq!(
                diagnostic_kind(diag),
                *expected_kind,
                "unexpected kind for {diag:?}"
            );
        }
    }

    #[test]
    fn conflict_kind_is_conflict() {
        let d = Diagnostic::Conflict("dump already in progress".into());
        assert_eq!(diagnostic_kind(&d), "conflict");
    }

    #[test]
    fn io_kind_is_io() {
        let d = Diagnostic::Io("failed to write /tmp/0001.zip: permission denied".into());
        assert_eq!(diagnostic_kind(&d), "io");
    }

    fn make_beol_detail() -> ProjectDetail {
        // Four data-models passed in already-sorted order (client layer sorts;
        // renderer passes them through as-is). Having all four here guards against
        // a renderer that truncates or reorders the slice.
        ProjectDetail {
            iri: "http://rdfh.ch/projects/yTerZGyxjZVqFMNNKXCDPF".into(),
            shortcode: "0801".into(),
            shortname: "beol".into(),
            longname: Some("Bernoulli-Euler Online".into()),
            status: ProjectStatus::Active,
            description: vec![ProjectDescription {
                value: "<b>BEOL</b> — early modern mathematics.".into(),
                language: Some("en".into()),
            }],
            keywords: vec!["Bernoulli".into(), "Euler".into(), "Mathematics".into()],
            data_models: vec![
                DataModelSummary {
                    name: "beol".into(),
                    iri: "http://api.dasch.swiss/ontology/0801/beol/v2".into(),
                },
                DataModelSummary {
                    name: "biblio".into(),
                    iri: "http://api.dasch.swiss/ontology/0801/biblio/v2".into(),
                },
                DataModelSummary {
                    name: "leibniz".into(),
                    iri: "http://api.dasch.swiss/ontology/0801/leibniz/v2".into(),
                },
                DataModelSummary {
                    name: "newton".into(),
                    iri: "http://api.dasch.swiss/ontology/0801/newton/v2".into(),
                },
            ],
        }
    }

    #[test]
    fn project_describe_json_full() {
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer
            .project_describe(&make_beol_detail(), &meta)
            .unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();

        // _meta present
        assert_eq!(parsed["_meta"]["auth"], "anonymous");
        assert_eq!(parsed["_meta"]["exit_code"], 0);

        // data is a single object
        let data = &parsed["data"];
        assert!(data.is_object());
        assert_eq!(
            data["iri"],
            "http://rdfh.ch/projects/yTerZGyxjZVqFMNNKXCDPF"
        );
        assert_eq!(data["shortcode"], "0801");
        assert_eq!(data["shortname"], "beol");
        assert_eq!(data["longname"], "Bernoulli-Euler Online");
        assert_eq!(data["status"], "active");

        // description array
        let desc = data["description"].as_array().unwrap();
        assert_eq!(desc.len(), 1);
        assert_eq!(desc[0]["value"], "<b>BEOL</b> — early modern mathematics.");
        assert_eq!(desc[0]["language"], "en");

        // keywords array
        let kws = data["keywords"].as_array().unwrap();
        assert_eq!(kws.len(), 3);
        assert_eq!(kws[0], "Bernoulli");

        // data_models array — four entries in sorted order (beol, biblio, leibniz, newton).
        // Guards against a renderer that truncates or reorders the slice.
        let dms = data["data_models"].as_array().unwrap();
        assert_eq!(dms.len(), 4, "all four data-models must be rendered");
        assert_eq!(dms[0]["name"], "beol");
        assert_eq!(
            dms[0]["iri"],
            "http://api.dasch.swiss/ontology/0801/beol/v2"
        );
        assert_eq!(dms[1]["name"], "biblio");
        assert_eq!(dms[2]["name"], "leibniz");
        assert_eq!(dms[3]["name"], "newton");
    }

    #[test]
    fn project_describe_json_no_longname() {
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let mut detail = make_beol_detail();
        detail.longname = None;
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.project_describe(&detail, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        // longname None → JSON null
        assert!(parsed["data"]["longname"].is_null());
    }

    #[test]
    fn project_describe_json_empty_fields() {
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let detail = ProjectDetail {
            iri: "http://rdfh.ch/projects/0000".into(),
            shortcode: "0000".into(),
            shortname: "minimal".into(),
            longname: None,
            status: ProjectStatus::Inactive,
            description: vec![],
            keywords: vec![],
            data_models: vec![],
        };
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.project_describe(&detail, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        let data = &parsed["data"];
        assert_eq!(data["status"], "inactive");
        assert!(data["description"].as_array().unwrap().is_empty());
        assert!(data["keywords"].as_array().unwrap().is_empty());
        assert!(data["data_models"].as_array().unwrap().is_empty());
    }

    fn make_data_model_fixture() -> Vec<DataModel> {
        vec![
            DataModel {
                name: "beol".into(),
                iri: "http://api.dasch.swiss/ontology/0801/beol/v2".into(),
                label: Some("The BEOL data-model".into()),
                last_modified: Some("2024-05-27T13:43:26.233048Z".into()),
                is_builtin: false,
            },
            DataModel {
                name: "biblio".into(),
                iri: "http://api.dasch.swiss/ontology/0801/biblio/v2".into(),
                label: None,
                last_modified: None,
                is_builtin: false,
            },
            DataModel {
                name: "knora-api".into(),
                iri: "http://api.knora.org/ontology/knora-api/v2".into(),
                label: None,
                last_modified: None,
                is_builtin: true,
            },
        ]
    }

    #[test]
    fn data_models_json_output() {
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let view = DataModelListView {
            items: make_data_model_fixture(),
            total: 3,
            filter: None,
        };
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.data_models(&view, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();

        // _meta present
        assert_eq!(parsed["_meta"]["auth"], "anonymous");
        assert_eq!(parsed["_meta"]["server"], "https://api.test.dasch.swiss");
        assert_eq!(parsed["_meta"]["exit_code"], 0);

        // data is an array
        let data = parsed["data"].as_array().unwrap();
        assert_eq!(data.len(), 3);

        // first item: has label and last_modified, not builtin
        assert_eq!(data[0]["name"], "beol");
        assert_eq!(
            data[0]["iri"],
            "http://api.dasch.swiss/ontology/0801/beol/v2"
        );
        assert_eq!(data[0]["label"], "The BEOL data-model");
        assert_eq!(data[0]["last_modified"], "2024-05-27T13:43:26.233048Z");
        assert_eq!(data[0]["is_builtin"], false);

        // second item: label None → null, last_modified None → null
        assert_eq!(data[1]["name"], "biblio");
        assert!(data[1]["label"].is_null());
        assert!(data[1]["last_modified"].is_null());
        assert_eq!(data[1]["is_builtin"], false);

        // third item: builtin, both null
        assert_eq!(data[2]["name"], "knora-api");
        assert!(data[2]["label"].is_null());
        assert!(data[2]["last_modified"].is_null());
        assert_eq!(data[2]["is_builtin"], true);
    }

    #[test]
    fn data_models_json_empty_data_array() {
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let view = DataModelListView {
            items: vec![],
            total: 0,
            filter: None,
        };
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.data_models(&view, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        assert!(parsed["data"].as_array().unwrap().is_empty());
    }

    // ── data_model_describe JSON tests ────────────────────────────────────────

    fn make_beol_dm_detail() -> DataModelDetail {
        DataModelDetail {
            name: "beol".into(),
            iri: "http://api.dasch.swiss/ontology/0801/beol/v2".into(),
            label: Some("The BEOL data-model".into()),
            last_modified: Some("2024-05-27T13:43:26.233048Z".into()),
            resource_types: vec![
                ResourceTypeSummary {
                    name: "Archive".into(),
                    iri: "http://api.dasch.swiss/ontology/0801/beol/v2#Archive".into(),
                    label: Some("Archive".into()),
                },
                ResourceTypeSummary {
                    name: "basicLetter".into(),
                    iri: "http://api.dasch.swiss/ontology/0801/beol/v2#basicLetter".into(),
                    label: None,
                },
                ResourceTypeSummary {
                    name: "letter".into(),
                    iri: "http://api.dasch.swiss/ontology/0801/beol/v2#letter".into(),
                    label: Some("Letter".into()),
                },
            ],
        }
    }

    #[test]
    fn data_model_describe_json_full() {
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer
            .data_model_describe(&make_beol_dm_detail(), &meta)
            .unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();

        // _meta present
        assert_eq!(parsed["_meta"]["auth"], "anonymous");
        assert_eq!(parsed["_meta"]["server"], "https://api.test.dasch.swiss");
        assert_eq!(parsed["_meta"]["exit_code"], 0);

        // data is a single object (ADR-0003)
        let data = &parsed["data"];
        assert!(data.is_object());
        assert_eq!(data["name"], "beol");
        assert_eq!(data["iri"], "http://api.dasch.swiss/ontology/0801/beol/v2");
        assert_eq!(data["label"], "The BEOL data-model");
        // last_modified is the full RFC3339 string (lossless)
        assert_eq!(data["last_modified"], "2024-05-27T13:43:26.233048Z");

        // resource_types array
        let rts = data["resource_types"].as_array().unwrap();
        assert_eq!(rts.len(), 3);
        assert_eq!(rts[0]["name"], "Archive");
        assert_eq!(
            rts[0]["iri"],
            "http://api.dasch.swiss/ontology/0801/beol/v2#Archive"
        );
        assert_eq!(rts[0]["label"], "Archive");
        // label None → null
        assert_eq!(rts[1]["name"], "basicLetter");
        assert!(rts[1]["label"].is_null());
        assert_eq!(rts[2]["name"], "letter");
        assert_eq!(rts[2]["label"], "Letter");
    }

    #[test]
    fn data_model_describe_json_no_label_no_last_modified() {
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let detail = DataModelDetail {
            name: "minimal".into(),
            iri: "http://api.dasch.swiss/ontology/0000/minimal/v2".into(),
            label: None,
            last_modified: None,
            resource_types: vec![],
        };
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.data_model_describe(&detail, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        let data = &parsed["data"];
        // label None → null
        assert!(data["label"].is_null());
        // last_modified None → null
        assert!(data["last_modified"].is_null());
        // resource_types empty array
        assert!(data["resource_types"].as_array().unwrap().is_empty());
    }

    // ── resource_types JSON tests ─────────────────────────────────────────────

    fn make_rt_fixture() -> Vec<ResourceType> {
        vec![
            ResourceType {
                name: "Archive".into(),
                iri: "http://api.dasch.swiss/ontology/0801/beol/v2#Archive".into(),
                label: Some("Archive".into()),
                is_builtin: false,
            },
            ResourceType {
                name: "letter".into(),
                iri: "http://api.dasch.swiss/ontology/0801/beol/v2#letter".into(),
                label: None,
                is_builtin: false,
            },
        ]
    }

    #[test]
    fn resource_types_json_output() {
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let view = ResourceTypeListView {
            items: make_rt_fixture(),
            total: 2,
            filter: None,
            data_model: "beol".into(),
        };
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.resource_types(&view, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();

        // _meta present
        assert_eq!(parsed["_meta"]["auth"], "anonymous");
        assert_eq!(parsed["_meta"]["server"], "https://api.test.dasch.swiss");
        assert_eq!(parsed["_meta"]["exit_code"], 0);

        // data is an array
        let data = parsed["data"].as_array().unwrap();
        assert_eq!(data.len(), 2);

        // first item: has label, not builtin
        assert_eq!(data[0]["name"], "Archive");
        assert_eq!(
            data[0]["iri"],
            "http://api.dasch.swiss/ontology/0801/beol/v2#Archive"
        );
        assert_eq!(data[0]["label"], "Archive");
        assert_eq!(data[0]["is_builtin"], false);

        // second item: label None → null
        assert_eq!(data[1]["name"], "letter");
        assert!(data[1]["label"].is_null());
        assert_eq!(data[1]["is_builtin"], false);
    }

    #[test]
    fn resource_types_json_with_builtins() {
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let view = ResourceTypeListView {
            items: vec![ResourceType {
                name: "Region".into(),
                iri: "http://api.knora.org/ontology/knora-api/v2#Region".into(),
                label: Some("Region".into()),
                is_builtin: true,
            }],
            total: 1,
            filter: None,
            data_model: "beol".into(),
        };
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.resource_types(&view, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        let data = parsed["data"].as_array().unwrap();
        assert_eq!(data.len(), 1);
        assert_eq!(data[0]["name"], "Region");
        assert_eq!(data[0]["label"], "Region");
        // is_builtin must be true (a bool, not a string)
        assert_eq!(data[0]["is_builtin"], true);
    }

    #[test]
    fn resource_types_json_with_filter() {
        // filter does not affect JSON output shape; just verify it renders cleanly
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let view = ResourceTypeListView {
            items: vec![make_rt_fixture().remove(0)], // just Archive
            total: 2,
            filter: Some("arch".to_string()),
            data_model: "beol".into(),
        };
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.resource_types(&view, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        let data = parsed["data"].as_array().unwrap();
        assert_eq!(data.len(), 1);
        assert_eq!(data[0]["name"], "Archive");
    }

    #[test]
    fn resource_types_json_empty_data_array() {
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let view = ResourceTypeListView {
            items: vec![],
            total: 0,
            filter: None,
            data_model: "beol".into(),
        };
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.resource_types(&view, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        assert!(parsed["data"].as_array().unwrap().is_empty());
    }

    // ── resource_describe JSON values tests ───────────────────────────────────

    use crate::model::resource_type::ValueType;
    use crate::model::{
        DatePoint, DateValue, FieldValues, FileValue, ResourceAccess, ResourceDetail,
        ResourceVisibility, Value, ValueContent,
    };

    fn make_resource_detail_no_values() -> ResourceDetail {
        ResourceDetail {
            label: "Test Resource".into(),
            iri: "http://rdfh.ch/0803/abc123".into(),
            resource_type: "Page".into(),
            ark_url: None,
            creation_date: None,
            last_modified: None,
            attached_project: None,
            owner: None,
            visibility: Some(ResourceVisibility::Public),
            your_access: Some(ResourceAccess::View),
            values: None,
        }
    }

    #[test]
    fn resource_describe_json_no_values_key_absent() {
        // When values is None, the "values" key must be ABSENT (not null) in json output.
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer
            .resource_describe(&make_resource_detail_no_values(), &meta)
            .unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        let data = &parsed["data"];
        assert!(
            data["values"].is_null() && !data.as_object().unwrap().contains_key("values"),
            "values key must be absent when values is None; got data: {data}"
        );
    }

    #[test]
    fn resource_describe_json_some_values_array_present() {
        // When values is Some, the "values" key must be present in json data.
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let mut detail = make_resource_detail_no_values();
        detail.values = Some(vec![FieldValues {
            name: "hasTitle".into(),
            label: Some("Title".into()),
            values: vec![ValueContent::Text("Hello".into()).into()],
        }]);
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.resource_describe(&detail, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        let data = &parsed["data"];
        assert!(
            data.as_object().unwrap().contains_key("values"),
            "values key must be present when values is Some; got data: {data}"
        );
        let values = data["values"].as_array().unwrap();
        assert_eq!(values.len(), 1);
        assert_eq!(values[0]["field"], "hasTitle");
        assert_eq!(values[0]["field_label"], "Title");
        let val_objs = values[0]["values"].as_array().unwrap();
        assert_eq!(val_objs.len(), 1);
        assert_eq!(val_objs[0]["value_type"], "text");
        assert_eq!(val_objs[0]["text"], "Hello");
    }

    #[test]
    fn resource_describe_json_some_empty_values_array() {
        // Some(vec![]) → "values": [] — key present, empty array.
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let mut detail = make_resource_detail_no_values();
        detail.values = Some(vec![]);
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.resource_describe(&detail, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        let data = &parsed["data"];
        assert!(
            data.as_object().unwrap().contains_key("values"),
            "values key must be present even for empty Some(vec![]);"
        );
        assert!(data["values"].as_array().unwrap().is_empty());
    }

    #[test]
    fn resource_describe_json_field_label_null_when_none() {
        // field_label null when label is None.
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let mut detail = make_resource_detail_no_values();
        detail.values = Some(vec![FieldValues {
            name: "seqnum".into(),
            label: None,
            values: vec![ValueContent::Integer(42).into()],
        }]);
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.resource_describe(&detail, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        let fg = &parsed["data"]["values"][0];
        assert!(
            fg["field_label"].is_null(),
            "field_label must be null when label is None"
        );
        let val = &fg["values"][0];
        assert_eq!(val["value_type"], "integer");
        assert_eq!(val["value"], 42);
    }

    #[test]
    fn resource_describe_json_link_value() {
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let mut detail = make_resource_detail_no_values();
        detail.values = Some(vec![FieldValues {
            name: "isPartOf".into(),
            label: None,
            values: vec![
                ValueContent::Link {
                    target_iri: "http://rdfh.ch/0803/book1".into(),
                    target_label: Some("My Book".into()),
                }
                .into(),
                ValueContent::Link {
                    target_iri: "http://rdfh.ch/0803/book2".into(),
                    target_label: None,
                }
                .into(),
            ],
        }]);
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.resource_describe(&detail, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        let vals = &parsed["data"]["values"][0]["values"];
        // first: with label
        assert_eq!(vals[0]["value_type"], "link");
        assert_eq!(vals[0]["target_iri"], "http://rdfh.ch/0803/book1");
        assert_eq!(vals[0]["target_label"], "My Book");
        // second: no label → null
        assert_eq!(vals[1]["value_type"], "link");
        assert_eq!(vals[1]["target_iri"], "http://rdfh.ch/0803/book2");
        assert!(vals[1]["target_label"].is_null());
    }

    #[test]
    fn resource_describe_json_still_image_value() {
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let mut detail = make_resource_detail_no_values();
        detail.values = Some(vec![FieldValues {
            name: "hasStillImageFileValue".into(),
            label: None,
            values: vec![
                ValueContent::File(FileValue {
                    value_type: ValueType::StillImage,
                    filename: "image.jp2".into(),
                    url: "https://iiif.example.com/image.jp2/full/max/0/default.jpg".into(),
                    width: Some(1200),
                    height: Some(800),
                })
                .into(),
            ],
        }]);
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.resource_describe(&detail, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        let val = &parsed["data"]["values"][0]["values"][0];
        assert_eq!(val["value_type"], "still-image");
        assert_eq!(val["filename"], "image.jp2");
        assert_eq!(
            val["url"],
            "https://iiif.example.com/image.jp2/full/max/0/default.jpg"
        );
        assert_eq!(val["width"], 1200);
        assert_eq!(val["height"], 800);
    }

    #[test]
    fn resource_describe_json_date_value() {
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let mut detail = make_resource_detail_no_values();
        let pt = DatePoint {
            year: Some(1489),
            month: None,
            day: None,
            era: Some("CE".into()),
        };
        detail.values = Some(vec![FieldValues {
            name: "hasDate".into(),
            label: None,
            values: vec![
                ValueContent::Date(DateValue {
                    calendar: "GREGORIAN".into(),
                    start: pt.clone(),
                    end: pt.clone(),
                })
                .into(),
            ],
        }]);
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.resource_describe(&detail, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        let val = &parsed["data"]["values"][0]["values"][0];
        assert_eq!(val["value_type"], "date");
        assert_eq!(val["calendar"], "GREGORIAN");
        assert_eq!(val["start"]["year"], 1489);
        assert_eq!(val["start"]["era"], "CE");
        assert!(val["start"]["month"].is_null());
        assert!(val["start"]["day"].is_null());
    }

    #[test]
    fn resource_describe_json_comment_present_when_set() {
        // A value with a comment carries a "comment" key in the value object.
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let mut detail = make_resource_detail_no_values();
        detail.values = Some(vec![FieldValues {
            name: "hasTranscription".into(),
            label: None,
            values: vec![Value {
                content: ValueContent::Text("some transcription".into()),
                comment: Some("reading uncertain".into()),
            }],
        }]);
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.resource_describe(&detail, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        let val = &parsed["data"]["values"][0]["values"][0];
        assert_eq!(val["value_type"], "text");
        assert_eq!(val["text"], "some transcription");
        assert_eq!(val["comment"], "reading uncertain");
    }

    #[test]
    fn resource_describe_json_comment_absent_when_none() {
        // A value with no comment must NOT carry a "comment" key at all (omit, not null).
        let out = SharedBuf::new();
        let mut renderer = JsonRenderer::with_writer(out.clone());
        let mut detail = make_resource_detail_no_values();
        detail.values = Some(vec![FieldValues {
            name: "hasTranscription".into(),
            label: None,
            values: vec![ValueContent::Text("plain transcription".into()).into()],
        }]);
        let meta = make_meta("anonymous", "https://api.test.dasch.swiss");
        renderer.resource_describe(&detail, &meta).unwrap();

        let parsed: serde_json::Value = serde_json::from_str(out.string().trim()).unwrap();
        let val = &parsed["data"]["values"][0]["values"][0];
        assert!(
            !val.as_object().unwrap().contains_key("comment"),
            "comment key must be absent when comment is None; got: {val}"
        );
    }
}