tix-tracker 0.10.0

//! The portable health document: one versioned DTO carrying everything health
//! knows, so the CLI, the TUI, MCP, and an export file all describe the same facts
//! (mission `project-issue-health-status-01M3C8HX`, WP04 T020/T021).
//!
//! # One DTO, or four opinions
//!
//! C-007 requires the CLI, the TUI, MCP, and the portable surfaces to consume **one**
//! health DTO. This is it. A surface renders it; a surface does not recompute it. The
//! consequence that matters is that `tix health --json`, the MCP `health` tool, and
//! `tix export --target health` cannot disagree, because there is no second
//! implementation to drift.
//!
//! # Loss-aware, not lossless-by-accident
//!
//! The document preserves the current state, its raw recorded value even when this
//! build cannot read it, the policy version, the events, the derived rollup with its
//! contributors, and every diagnostic. It also carries the fields a *future* build
//! adds: `#[serde(flatten)] extensions` keeps unknown keys verbatim, exactly as the
//! views document does for the same reason — a round trip through a build that
//! predates a field must not delete it (C-008).
//!
//! # Round trips are idempotent
//!
//! `document → JSON → document → JSON` is byte-stable: [`PortableHealth::from_json`]
//! re-derives the diagnostics this build can see from the data it read and merges
//! them into the ones the document carried, *recognizing* an equivalent diagnostic
//! rather than appending a duplicate ([`HealthDiagnostic::same_as`]). Without that,
//! every round trip would grow the diagnostic list — which is the difference between
//! a document that can be committed and one that cannot.

use serde::{Deserialize, Serialize};
use toml::Table;

use crate::error::{Result, TixError};
use crate::model::Issue;

use super::diagnostics::{HealthDiagnostic, HealthDiagnosticKind, RemoteTarget};
use super::events::{HealthScope, HealthSource, project};
use super::index::HealthIndex;
use super::policy::HealthPolicy;
use super::rollup::{Contribution, HealthRollup, rollup};
use super::state::HealthState;

/// The document's format marker.
pub const FORMAT: &str = "tix-health";

/// The document's format version. Bumped when the shape changes incompatibly.
pub const VERSION: u32 = 1;

/// Everything health knows, in one versioned document (T020).
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct PortableHealth {
    /// The format marker: [`FORMAT`].
    pub format: String,
    /// The format version: [`VERSION`].
    pub version: u32,
    /// The policy version every derived value in this document was computed under.
    pub policy_version: String,
    /// One entry per scope, in a stable order.
    #[serde(default)]
    pub scopes: Vec<PortableScopeHealth>,
    /// Every diagnostic, in a stable order.
    #[serde(default)]
    pub diagnostics: Vec<PortableHealthDiagnostic>,
    /// Keys this build does not interpret, preserved verbatim.
    #[serde(flatten)]
    pub extensions: Table,
}

/// One scope's health, as a surface or a file sees it.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct PortableScopeHealth {
    /// The scope's canonical spelling (`issue:42`, `cycle:2026-10`). A stable id,
    /// never a display name (C-002).
    pub scope: String,
    /// The state to display.
    pub state: String,
    /// How the value was obtained (`current`, `derived`, `override`).
    pub source: String,
    /// The policy version the *file* records, when it records one.
    #[serde(default)]
    pub recorded_policy_version: Option<String>,
    /// When the value was last updated, when the file says.
    #[serde(default)]
    pub updated_at: Option<String>,
    /// The raw stored value — including one this build cannot read, so a round trip
    /// through this build preserves what it does not understand (C-008).
    #[serde(default)]
    pub recorded: Option<String>,
    /// The health History entries about this scope, verbatim.
    #[serde(default)]
    pub events: Vec<PortableHealthEvent>,
    /// The derived rollup, when the scope has contributors.
    #[serde(default)]
    pub rollup: Option<PortableRollup>,
}

/// One health History entry, preserved exactly as the issue records it.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct PortableHealthEvent {
    /// The entry's kind (`health_updated`, `health_overridden`).
    pub kind: String,
    /// When it happened, RFC 3339, as recorded.
    pub timestamp: String,
    /// Who did it, as recorded.
    pub actor: String,
    /// The entry's detail, verbatim — this build does not re-parse it, so it cannot
    /// lose what it does not understand.
    pub detail: String,
}

/// A derived rollup, with its contributors.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct PortableRollup {
    /// The derived state.
    pub state: String,
    /// The policy version it was derived under.
    pub policy_version: String,
    /// How the state was obtained.
    pub source: String,
    /// The contributors, in issue order.
    #[serde(default)]
    pub contributors: Vec<PortableContribution>,
}

/// One contributor to a rollup.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct PortableContribution {
    /// The contributing issue.
    pub number: u32,
    /// The state it carries.
    pub state: String,
    /// The raw stored value, when it could not be read.
    #[serde(default)]
    pub recorded: Option<String>,
}

/// One diagnostic, in the wire vocabulary (C-007's shared DTO).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct PortableHealthDiagnostic {
    /// The stable contract name (see [`HealthDiagnosticKind::ALL`]).
    pub kind: String,
    /// The scope's canonical spelling.
    pub scope: String,
    /// The unresolved reference, when there is one.
    #[serde(default)]
    pub reference: Option<String>,
    /// The field the problem sits at, when there is one.
    #[serde(default)]
    pub field: Option<String>,
    /// The remote target, when the problem is about a mapping.
    #[serde(default)]
    pub target: Option<String>,
    /// The raw recorded state, when the file records one this build cannot read.
    #[serde(default)]
    pub state: Option<String>,
    /// What is wrong.
    pub message: String,
    /// What to do about it.
    #[serde(default)]
    pub remedy: Option<String>,
}

impl PortableHealthDiagnostic {
    /// Project a diagnostic into the wire vocabulary.
    pub fn from_diagnostic(diagnostic: &HealthDiagnostic) -> Self {
        Self {
            kind: diagnostic.kind.as_str().to_string(),
            scope: diagnostic.scope.as_str(),
            reference: diagnostic.reference.clone(),
            field: diagnostic.field.clone(),
            target: diagnostic.target.map(|target| target.as_str().to_string()),
            state: diagnostic.state.clone(),
            message: diagnostic.message.clone(),
            remedy: diagnostic.remedy.clone(),
        }
    }

    /// Read the wire vocabulary back into a diagnostic.
    ///
    /// A kind this build does not know is read as [`HealthDiagnosticKind::PolicyMismatch`]
    /// — the value is kept, and the fact that this build cannot interpret it is
    /// itself the diagnostic — never dropped (C-008).
    pub fn to_diagnostic(&self) -> HealthDiagnostic {
        let kind = HealthDiagnosticKind::ALL
            .into_iter()
            .find(|kind| kind.as_str() == self.kind)
            .unwrap_or(HealthDiagnosticKind::PolicyMismatch);
        // A scope spelling this build does not know is kept as a reference rather
        // than dropped: the diagnostic survives, and it says which scope it could
        // not read (C-008).
        let scope = HealthScope::parse(&self.scope).unwrap_or(HealthScope::Issue(0));
        let target = RemoteTarget::ALL
            .into_iter()
            .find(|candidate| Some(candidate.as_str().to_string()) == self.target);
        let mut diagnostic = HealthDiagnostic::new(kind, scope, self.message.clone());
        diagnostic.reference = self.reference.clone().or_else(|| {
            HealthScope::parse(&self.scope)
                .is_none()
                .then(|| self.scope.clone())
        });
        diagnostic.field = self.field.clone();
        diagnostic.target = target;
        diagnostic.state = self.state.clone();
        diagnostic.remedy = self.remedy.clone();
        diagnostic
    }

    /// Whether two entries describe the same diagnostic.
    pub fn same_as(&self, other: &Self) -> bool {
        self == other
    }
}

impl PortableHealth {
    /// Build the document from a repository's issues (T020).
    ///
    /// One pass builds the index; every scope with contributors gets a rollup; and
    /// each issue's health History entries are carried verbatim. Nothing is
    /// recomputed from the remote, and no file is written.
    pub fn build(
        issues: &[Issue],
        cycles: &[String],
        milestones: &[String],
        policy: &HealthPolicy,
    ) -> Self {
        let index = HealthIndex::build(issues, cycles, milestones, policy);
        let mut scopes: Vec<PortableScopeHealth> = Vec::new();

        // A scope per issue that records anything, plus every scope with contributors.
        for issue in issues {
            let view = project(issue, policy);
            let scope = HealthScope::of_issue(issue.number);
            let events: Vec<PortableHealthEvent> = issue
                .history
                .events()
                .into_iter()
                .filter(|entry| {
                    matches!(
                        entry.kind,
                        crate::model::HistoryEventKind::HealthUpdated
                            | crate::model::HistoryEventKind::HealthOverridden
                    )
                })
                .map(|entry| PortableHealthEvent {
                    kind: entry.kind.as_str().to_string(),
                    timestamp: entry.timestamp.clone(),
                    actor: entry.actor.clone(),
                    detail: entry.detail.clone(),
                })
                .collect();
            // Every issue is in the document, including one that records nothing:
            // C-006 requires a legacy issue to display an explicit `unknown`, and a
            // document that omitted it would leave every consumer to invent that
            // entry — which is how four surfaces come to disagree.
            let recorded = view.recorded.clone();
            scopes.push(PortableScopeHealth {
                scope: scope.as_str(),
                state: view.state.as_str().to_string(),
                source: view.source.as_str().to_string(),
                recorded_policy_version: view.policy_version.clone(),
                updated_at: view.updated_at.clone(),
                recorded,
                events,
                rollup: None,
            });
        }

        // One row per issue the repository *has*, plus one per contributing scope (a
        // cycle, a milestone). An issue number the files only mention — a `parent:` that
        // no longer resolves — gets its diagnostic and no row: giving it a row would
        // make a summary count a scope that does not exist.
        let known: std::collections::BTreeSet<u32> =
            issues.iter().map(|issue| issue.number).collect();
        for scope in index.scopes() {
            if let HealthScope::Issue(number) = scope {
                if !known.contains(&number) {
                    continue;
                }
            }
            let derived = rollup(&index, &scope, policy);
            let entry = PortableScopeHealth::from_rollup(&derived);
            match scopes
                .iter_mut()
                .find(|entry| entry.scope == scope.as_str())
            {
                Some(existing) => existing.rollup = entry.rollup,
                None => scopes.push(entry),
            }
        }
        scopes.sort_by(|left, right| left.scope.cmp(&right.scope));

        let mut document = Self {
            format: FORMAT.to_string(),
            version: VERSION,
            policy_version: policy.version().to_string(),
            scopes,
            diagnostics: index
                .diagnostics()
                .iter()
                .map(PortableHealthDiagnostic::from_diagnostic)
                .collect(),
            extensions: Table::new(),
        };
        document.refresh_diagnostics();
        document
    }

    /// Serialize as compact, byte-stable JSON.
    pub fn to_json(&self) -> Result<String> {
        serde_json::to_string(self)
            .map_err(|error| TixError::Parse(format!("portable health document: {error}")))
    }

    /// Serialize as indented JSON — what a human reads.
    pub fn to_json_pretty(&self) -> Result<String> {
        serde_json::to_string_pretty(self)
            .map_err(|error| TixError::Parse(format!("portable health document: {error}")))
    }

    /// Read a portable document, re-deriving what this build can see (T021).
    pub fn from_json(text: &str) -> Result<Self> {
        let mut document: Self = serde_json::from_str(text)
            .map_err(|error| TixError::Parse(format!("portable health document: {error}")))?;
        document.refresh_diagnostics();
        Ok(document)
    }

    /// The diagnostics this document's own data implies.
    ///
    /// Derived, never stored: a rollup's silent contributors and a scope's own
    /// findings are facts about the data, so a document that arrives without them
    /// gains them on read rather than being trusted to have carried them.
    pub fn derived_diagnostics(&self) -> Vec<HealthDiagnostic> {
        let mut derived: Vec<HealthDiagnostic> = Vec::new();
        for scope in &self.scopes {
            let Some(rollup) = &scope.rollup else {
                continue;
            };
            for contributor in &rollup.contributors {
                if contributor.state != HealthState::Unknown.as_str() {
                    continue;
                }
                let scope_id = HealthScope::parse(&scope.scope).unwrap_or(HealthScope::Issue(0));
                let message = match &contributor.recorded {
                    Some(raw) => format!(
                        "issue #{} records health `{raw}`, which this build cannot read",
                        contributor.number
                    ),
                    None => format!("issue #{} records no health", contributor.number),
                };
                let mut diagnostic =
                    HealthDiagnostic::new(HealthDiagnosticKind::UnknownHealth, scope_id, message);
                diagnostic.state = contributor.recorded.clone();
                derived.push(diagnostic);
            }
        }
        derived
    }

    /// Merge the derived diagnostics into the carried ones, without duplicating.
    ///
    /// Idempotent by design (T021): a diagnostic a previous round trip stored is
    /// recognized rather than appended again, so the document stabilizes after one
    /// write instead of growing on every read.
    pub fn refresh_diagnostics(&mut self) {
        let derived = self.derived_diagnostics();
        let derived_wire: Vec<PortableHealthDiagnostic> = derived
            .iter()
            .map(PortableHealthDiagnostic::from_diagnostic)
            .collect();
        let mut merged: Vec<PortableHealthDiagnostic> =
            Vec::with_capacity(self.diagnostics.len() + derived_wire.len());
        for diagnostic in self.diagnostics.iter().chain(derived_wire.iter()) {
            if !merged.iter().any(|seen| seen.same_as(diagnostic)) {
                merged.push(diagnostic.clone());
            }
        }
        self.diagnostics = merged;
    }

    /// One scope's entry.
    pub fn scope(&self, scope: &HealthScope) -> Option<&PortableScopeHealth> {
        let id = scope.as_str();
        self.scopes.iter().find(|entry| entry.scope == id)
    }

    /// The diagnostics about one scope.
    pub fn diagnostics_for(&self, scope: &HealthScope) -> Vec<&PortableHealthDiagnostic> {
        let id = scope.as_str();
        self.diagnostics
            .iter()
            .filter(|diagnostic| diagnostic.scope == id)
            .collect()
    }

    /// Whether this document carries data this build cannot interpret — a newer
    /// policy version, or an unknown diagnostic kind. A surface says so rather than
    /// rendering a value it cannot vouch for (C-008).
    pub fn carries_unknown_data(&self) -> bool {
        let known = HealthDiagnosticKind::ALL.map(HealthDiagnosticKind::as_str);
        self.diagnostics
            .iter()
            .any(|diagnostic| !known.contains(&diagnostic.kind.as_str()))
    }
}

impl PortableScopeHealth {
    /// A scope entry carrying only a derived rollup.
    pub fn from_rollup(derived: &HealthRollup) -> Self {
        Self {
            scope: derived.scope.as_str(),
            state: derived.state.as_str().to_string(),
            source: HealthSource::Derived.as_str().to_string(),
            recorded_policy_version: None,
            updated_at: None,
            recorded: None,
            events: Vec::new(),
            rollup: Some(PortableRollup {
                state: derived.state.as_str().to_string(),
                policy_version: derived.policy_version.clone(),
                source: derived.source.as_str().to_string(),
                contributors: derived.contributions.iter().map(contribution).collect(),
            }),
        }
    }
}

fn contribution(value: &Contribution) -> PortableContribution {
    PortableContribution {
        number: value.number,
        state: value.state.as_str().to_string(),
        recorded: value.recorded.clone(),
    }
}

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

    fn issue(number: u32, parent: Option<u32>, health: Option<&str>) -> Issue {
        let parent = parent.map_or(String::new(), |p| format!("parent: {p}\n"));
        let health = health
            .map(|state| format!("health:\n  state: {state}\n"))
            .unwrap_or_default();
        let contents = format!(
            "---\nnumber: {number}\ntitle: \"Issue {number}\"\nstatus: \"todo\"\n\
             created: \"2026-01-01\"\nupdated: \"2026-01-01\"\n{parent}{health}---\n\nBody.\n"
        );
        let mut issue = Issue::parse(&contents).expect("the fixture parses");
        issue.filename = format!("issue-{number}.md");
        issue
    }

    #[test]
    fn portable_health_round_trips_and_is_idempotent() {
        let policy = HealthPolicy::v1();
        let issues = vec![
            issue(1, None, Some("on_track")),
            issue(2, Some(1), Some("at_risk")),
            issue(3, Some(1), None),
        ];
        let document = PortableHealth::build(&issues, &[], &[], &policy);
        assert_eq!(document.format, FORMAT);
        assert_eq!(document.version, VERSION);
        assert_eq!(document.policy_version, "health-v1");

        let first = document.to_json().expect("serializes");
        let read = PortableHealth::from_json(&first).expect("reads back");
        assert_eq!(
            read, document,
            "the document is a fixed point of the round trip"
        );
        let second = read.to_json().expect("serializes again");
        assert_eq!(first, second, "JSON is byte-stable across round trips");
        assert_eq!(read.diagnostics.len(), document.diagnostics.len());

        // The parent's derived rollup carries its contributors, and the child with
        // no health is named rather than dropped.
        let parent = document.scope(&HealthScope::Issue(1)).expect("the parent");
        let rollup = parent.rollup.as_ref().expect("a derived rollup");
        assert_eq!(rollup.state, "at_risk");
        assert_eq!(rollup.contributors.len(), 2);
        assert_eq!(rollup.contributors[0].number, 2);
        assert!(
            document
                .diagnostics
                .iter()
                .any(|d| d.kind == "unknown_health" && d.scope == "issue:1")
        );
    }

    #[test]
    fn portable_health_preserves_what_this_build_cannot_read() {
        let policy = HealthPolicy::v1();
        let issues = vec![
            issue(1, None, Some("on_track")),
            issue(2, Some(1), Some("from_the_future")),
        ];
        let document = PortableHealth::build(&issues, &[], &[], &policy);
        let child = document.scope(&HealthScope::Issue(2)).expect("the child");
        assert_eq!(child.recorded.as_deref(), Some("from_the_future"));
        assert_eq!(child.state, "unknown");
        assert!(
            document
                .diagnostics
                .iter()
                .any(|d| d.kind == "invalid_state")
        );

        // And an unknown top-level key survives the round trip verbatim.
        let json = document.to_json().expect("serializes");
        let widened = json.replace(
            "\"policy_version\"",
            "\"future_section\":{\"nested\":7},\"policy_version\"",
        );
        let read = PortableHealth::from_json(&widened).expect("reads a newer document");
        assert!(
            read.extensions.contains_key("future_section"),
            "an unknown key is kept, not dropped"
        );
        assert!(
            read.to_json()
                .expect("serializes")
                .contains("future_section")
        );
    }

    #[test]
    fn portable_health_reads_an_unknown_diagnostic_kind_without_losing_it() {
        let document = PortableHealth::from_json(
            r#"{"format":"tix-health","version":1,"policy_version":"health-v9",
                "scopes":[],
                "diagnostics":[{"kind":"invented_by_a_newer_build","scope":"issue:4",
                                "message":"something this build does not know"}]}"#,
        )
        .expect("reads");
        assert!(document.carries_unknown_data());
        let diagnostic = document.diagnostics[0].to_diagnostic();
        assert_eq!(diagnostic.message, "something this build does not know");
        assert_eq!(diagnostic.scope, HealthScope::Issue(4));
        assert_eq!(
            diagnostic.kind,
            HealthDiagnosticKind::PolicyMismatch,
            "an unrecognized kind is reported, not dropped"
        );
    }
}