dpp-rules 0.2.0

//! Battery recycled content validation — EU Regulation 2023/1542, Art. 8 + Annex X.
//!
//! Art. 8 and Annex X set minimum recycled content targets for four metals.
//! Phase 1 (from 18 Aug 2031) covers **EV batteries, SLI batteries, and
//! industrial batteries with a capacity > 2 kWh** (excluding those with
//! exclusively external storage). **LMT batteries** join only in Phase 2 (from
//! **18 Aug 2036**), at the higher targets. Portable batteries are out of scope.
//!
//! The targets are **finalized law** — they are in the regulation text itself,
//! not in a pending delegated act. However, neither phase is yet in force.
//! The battery plugin therefore returns `NOT_ASSESSED` today; these constants
//! are the single source of truth that the plugin will check against once
//! enforcement begins.
//!
//! ## Phase 1 — EV + SLI + industrial > 2 kWh, from **18 Aug 2031** (Art. 8)
//! | Material | Minimum % |
//! |----------|-----------|
//! | Cobalt   |      16 % |
//! | Lead     |      85 % |
//! | Lithium  |       6 % |
//! | Nickel   |       6 % |
//!
//! ## Phase 2 — Phase 1 categories + **LMT**, from **18 Aug 2036** (Art. 8)
//! | Material | Minimum % |
//! |----------|-----------|
//! | Cobalt   |      26 % |
//! | Lead     |      85 % |
//! | Lithium  |      12 % |
//! | Nickel   |      15 % |

use alloc::vec::Vec;

// ✅ COMPLIANCE-PIN: EU 2023/1542, Art. 8 + Annex X (OJ L 2023/1542, 28 Jul 2023)
// Percentages: verified correct per Annex X.
// Phase-1 date: 18 Aug 2031. Phase-2 date: 18 Aug 2036.
// Category scope (corrected 2026-06-22, audit H-2): Phase 1 = EV + SLI + industrial
// > 2 kWh (excl. exclusively-external-storage); LMT batteries join only in Phase 2
// (LMT minimum content from 18 Aug 2036). SLI is **in** Phase-1 scope — a prior note
// here wrongly excluded it. Reconciled against multiple authoritative secondary
// sources (White & Case, EUR-Lex summary, GLEIF-independent battery guidance); the
// 🟠 residual is verbatim OJ Art. 8(2)/(3) confirmation, blocked here by EUR-Lex
// JavaScript rendering. Numeric percentages/dates are not in dispute.

// ── Phase 1 constants — EV + industrial ≥ 2 kWh from 18 Aug 2031 ─────────────

/// Minimum cobalt recycled content — Art. 8 + Annex X Phase 1, from 18 Aug 2031.
pub const COBALT_RECYCLED_PCT_2031: f64 = 16.0;
/// Minimum lead recycled content — Art. 8 + Annex X Phase 1, from 18 Aug 2031.
pub const LEAD_RECYCLED_PCT_2031: f64 = 85.0;
/// Minimum lithium recycled content — Art. 8 + Annex X Phase 1, from 18 Aug 2031.
pub const LITHIUM_RECYCLED_PCT_2031: f64 = 6.0;
/// Minimum nickel recycled content — Art. 8 + Annex X Phase 1, from 18 Aug 2031.
pub const NICKEL_RECYCLED_PCT_2031: f64 = 6.0;

// ── Phase 2 constants — EV + industrial ≥ 2 kWh + LMT from 18 Aug 2036 ───────

/// Minimum cobalt recycled content — Art. 8 + Annex X Phase 2, from 18 Aug 2036.
pub const COBALT_RECYCLED_PCT_2036: f64 = 26.0;
/// Minimum lead recycled content — Art. 8 + Annex X Phase 2, from 18 Aug 2036.
pub const LEAD_RECYCLED_PCT_2036: f64 = 85.0;
/// Minimum lithium recycled content — Art. 8 + Annex X Phase 2, from 18 Aug 2036.
pub const LITHIUM_RECYCLED_PCT_2036: f64 = 12.0;
/// Minimum nickel recycled content — Art. 8 + Annex X Phase 2, from 18 Aug 2036.
pub const NICKEL_RECYCLED_PCT_2036: f64 = 15.0;

// ── Input type ────────────────────────────────────────────────────────────────

/// Declared recycled content percentages for the four regulated metals.
///
/// `None` means the metal is absent or undeclared — it is skipped in target
/// checks. Only declared values can fail a target check.
#[derive(Debug, Clone, Copy)]
pub struct RecycledContentInput {
    pub cobalt_pct: Option<f64>,
    pub lithium_pct: Option<f64>,
    pub nickel_pct: Option<f64>,
    pub lead_pct: Option<f64>,
}

/// A recycled-content shortfall for a single material.
#[derive(Debug, Clone, Copy)]
pub struct RecycledContentShortfall {
    pub material: &'static str,
    pub declared_pct: f64,
    pub required_pct: f64,
}

// ── Phase-check functions ─────────────────────────────────────────────────────

/// Check declared recycled content against Annex X Phase 1 targets (from 2031).
///
/// Returns every material whose declared percentage falls below the Phase 1
/// minimum. An empty `Vec` means all declared metals pass. Undeclared metals
/// are not checked — battery-type scoping (Phase 1: EV / SLI / industrial
/// > 2 kWh; LMT only from Phase 2) is the caller's responsibility.
#[must_use]
pub fn annex_x_shortfalls_2031(input: &RecycledContentInput) -> Vec<RecycledContentShortfall> {
    check_targets(
        input,
        COBALT_RECYCLED_PCT_2031,
        LEAD_RECYCLED_PCT_2031,
        LITHIUM_RECYCLED_PCT_2031,
        NICKEL_RECYCLED_PCT_2031,
    )
}

/// Check declared recycled content against Annex X Phase 2 targets (from 2036).
#[must_use]
pub fn annex_x_shortfalls_2036(input: &RecycledContentInput) -> Vec<RecycledContentShortfall> {
    check_targets(
        input,
        COBALT_RECYCLED_PCT_2036,
        LEAD_RECYCLED_PCT_2036,
        LITHIUM_RECYCLED_PCT_2036,
        NICKEL_RECYCLED_PCT_2036,
    )
}

fn check_targets(
    input: &RecycledContentInput,
    cobalt_req: f64,
    lead_req: f64,
    lithium_req: f64,
    nickel_req: f64,
) -> Vec<RecycledContentShortfall> {
    let mut out = Vec::new();
    if let Some(pct) = input.cobalt_pct {
        // Non-finite (NaN/Inf) cannot demonstrate compliance — treat as shortfall.
        if !pct.is_finite() || pct < cobalt_req {
            out.push(RecycledContentShortfall {
                material: "cobalt",
                declared_pct: pct,
                required_pct: cobalt_req,
            });
        }
    }
    if let Some(pct) = input.lead_pct
        && (!pct.is_finite() || pct < lead_req)
    {
        out.push(RecycledContentShortfall {
            material: "lead",
            declared_pct: pct,
            required_pct: lead_req,
        });
    }
    if let Some(pct) = input.lithium_pct
        && (!pct.is_finite() || pct < lithium_req)
    {
        out.push(RecycledContentShortfall {
            material: "lithium",
            declared_pct: pct,
            required_pct: lithium_req,
        });
    }
    if let Some(pct) = input.nickel_pct
        && (!pct.is_finite() || pct < nickel_req)
    {
        out.push(RecycledContentShortfall {
            material: "nickel",
            declared_pct: pct,
            required_pct: nickel_req,
        });
    }
    out
}

// ── Chemistry → regulated-metal applicability ──────────────────────────────────

/// The Annex X regulated metals (cobalt, lithium, nickel, lead) that are
/// *meaningfully present* for a given battery chemistry.
///
/// Used to scope recycled-content checks so a chemistry that does not contain a
/// metal is never flagged for that metal's "shortfall" — e.g. an LFP cell
/// (LiFePO₄, no cobalt or nickel) must not produce a cobalt shortfall just
/// because the field defaulted to `0.0`.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct RegulatedMetals {
    pub cobalt: bool,
    pub lithium: bool,
    pub nickel: bool,
    pub lead: bool,
}

/// Map a battery chemistry code (e.g. `"LFP"`, `"NMC"`, `"lead-acid"`) to the
/// Annex X regulated metals it contains.
///
/// Matching is case-insensitive. Unknown chemistries return **all `true`**
/// (conservative: every declared value is checked, since we cannot rule a metal
/// out). The caller still skips any metal whose declared percentage is absent.
#[must_use]
pub fn chemistry_regulated_metals(chemistry: &str) -> RegulatedMetals {
    let c = chemistry.trim();
    let eq = |s: &str| c.eq_ignore_ascii_case(s);
    if eq("LFP") {
        RegulatedMetals {
            cobalt: false,
            lithium: true,
            nickel: false,
            lead: false,
        }
    } else if eq("NMC") || eq("NCA") {
        RegulatedMetals {
            cobalt: true,
            lithium: true,
            nickel: true,
            lead: false,
        }
    } else if eq("LCO") {
        RegulatedMetals {
            cobalt: true,
            lithium: true,
            nickel: false,
            lead: false,
        }
    } else if eq("NiMH") || eq("NiCd") {
        RegulatedMetals {
            cobalt: false,
            lithium: false,
            nickel: true,
            lead: false,
        }
    } else if eq("lead-acid") {
        RegulatedMetals {
            cobalt: false,
            lithium: false,
            nickel: false,
            lead: true,
        }
    } else if eq("solid-state") {
        RegulatedMetals {
            cobalt: false,
            lithium: true,
            nickel: false,
            lead: false,
        }
    } else {
        // Unknown chemistry — cannot exclude any metal; check whatever is declared.
        RegulatedMetals {
            cobalt: true,
            lithium: true,
            nickel: true,
            lead: true,
        }
    }
}

/// Metals whose recycled content is declared **> 0** but which the chemistry
/// does **not** contain — a data-integrity contradiction (e.g. cobalt recycled
/// content on an LFP cell, which has no cobalt).
///
/// A declared `0.0` is *not* a conflict (it states "no recycled content", which
/// is trivially true for an absent metal). Unknown chemistries contain every
/// metal per [`chemistry_regulated_metals`], so they never conflict.
#[must_use]
pub fn recycled_content_chemistry_conflicts(
    chemistry: &str,
    cobalt_pct: Option<f64>,
    lithium_pct: Option<f64>,
    nickel_pct: Option<f64>,
    lead_pct: Option<f64>,
) -> Vec<&'static str> {
    let reg = chemistry_regulated_metals(chemistry);
    let positive = |v: Option<f64>| matches!(v, Some(x) if x.is_finite() && x > 0.0);
    let mut out = Vec::new();
    if positive(cobalt_pct) && !reg.cobalt {
        out.push("cobalt");
    }
    if positive(lithium_pct) && !reg.lithium {
        out.push("lithium");
    }
    if positive(nickel_pct) && !reg.nickel {
        out.push("nickel");
    }
    if positive(lead_pct) && !reg.lead {
        out.push("lead");
    }
    out
}

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

    fn all_metals(co: f64, pb: f64, li: f64, ni: f64) -> RecycledContentInput {
        RecycledContentInput {
            cobalt_pct: Some(co),
            lead_pct: Some(pb),
            lithium_pct: Some(li),
            nickel_pct: Some(ni),
        }
    }

    #[test]
    fn exactly_at_2031_targets_passes() {
        let input = all_metals(16.0, 85.0, 6.0, 6.0);
        assert!(annex_x_shortfalls_2031(&input).is_empty());
    }

    #[test]
    fn above_2031_targets_passes() {
        let input = all_metals(20.0, 90.0, 10.0, 10.0);
        assert!(annex_x_shortfalls_2031(&input).is_empty());
    }

    #[test]
    fn below_2031_cobalt_flagged() {
        let input = all_metals(15.0, 85.0, 6.0, 6.0); // cobalt 15 < 16
        let shortfalls = annex_x_shortfalls_2031(&input);
        assert_eq!(shortfalls.len(), 1);
        assert_eq!(shortfalls[0].material, "cobalt");
        assert_eq!(shortfalls[0].required_pct, 16.0);
    }

    #[test]
    fn multiple_shortfalls_all_returned() {
        let input = all_metals(10.0, 80.0, 3.0, 4.0); // all below
        assert_eq!(annex_x_shortfalls_2031(&input).len(), 4);
    }

    #[test]
    fn undeclared_metals_not_flagged() {
        let input = RecycledContentInput {
            cobalt_pct: Some(20.0),
            lead_pct: None,
            lithium_pct: None,
            nickel_pct: None,
        };
        assert!(annex_x_shortfalls_2031(&input).is_empty());
    }

    #[test]
    fn phase2_stricter_than_phase1() {
        // 16% cobalt passes 2031 but fails 2036 (target 26%)
        let input = all_metals(16.0, 85.0, 6.0, 6.0);
        assert!(annex_x_shortfalls_2031(&input).is_empty());
        let shortfalls = annex_x_shortfalls_2036(&input);
        assert!(shortfalls.iter().any(|s| s.material == "cobalt"));
    }

    #[test]
    fn nan_cobalt_treated_as_shortfall() {
        let input = RecycledContentInput {
            cobalt_pct: Some(f64::NAN),
            lead_pct: None,
            lithium_pct: None,
            nickel_pct: None,
        };
        let shortfalls = annex_x_shortfalls_2031(&input);
        assert_eq!(shortfalls.len(), 1);
        assert_eq!(shortfalls[0].material, "cobalt");
    }

    #[test]
    fn infinity_cobalt_treated_as_shortfall() {
        let input = RecycledContentInput {
            cobalt_pct: Some(f64::INFINITY),
            lead_pct: None,
            lithium_pct: None,
            nickel_pct: None,
        };
        let shortfalls = annex_x_shortfalls_2031(&input);
        assert_eq!(shortfalls.len(), 1);
        assert_eq!(shortfalls[0].material, "cobalt");
    }

    #[test]
    fn lfp_regulates_lithium_only() {
        let m = chemistry_regulated_metals("LFP");
        assert!(m.lithium);
        assert!(!m.cobalt && !m.nickel && !m.lead);
        // case-insensitive
        assert_eq!(chemistry_regulated_metals("lfp"), m);
    }

    #[test]
    fn nmc_and_nca_regulate_cobalt_lithium_nickel() {
        for chem in ["NMC", "NCA"] {
            let m = chemistry_regulated_metals(chem);
            assert!(m.cobalt && m.lithium && m.nickel);
            assert!(!m.lead);
        }
    }

    #[test]
    fn lead_acid_regulates_lead_only() {
        let m = chemistry_regulated_metals("lead-acid");
        assert!(m.lead);
        assert!(!m.cobalt && !m.lithium && !m.nickel);
    }

    #[test]
    fn unknown_chemistry_checks_all_metals() {
        let m = chemistry_regulated_metals("mystery-cell");
        assert!(m.cobalt && m.lithium && m.nickel && m.lead);
    }

    #[test]
    fn positive_cobalt_on_lfp_is_a_conflict() {
        let c = recycled_content_chemistry_conflicts("LFP", Some(5.0), Some(12.0), None, None);
        assert_eq!(c.len(), 1);
        assert_eq!(c[0], "cobalt");
    }

    #[test]
    fn zero_cobalt_on_lfp_is_not_a_conflict() {
        // 0.0 declares "no recycled cobalt" — trivially true for an absent metal.
        let c = recycled_content_chemistry_conflicts("LFP", Some(0.0), Some(12.0), Some(0.0), None);
        assert!(c.is_empty(), "got: {c:?}");
    }

    #[test]
    fn nmc_cobalt_and_nickel_declared_no_conflict() {
        let c = recycled_content_chemistry_conflicts("NMC", Some(16.0), Some(6.0), Some(8.0), None);
        assert!(c.is_empty(), "got: {c:?}");
    }

    #[test]
    fn lead_declared_on_lfp_is_a_conflict() {
        let c = recycled_content_chemistry_conflicts("LFP", None, Some(12.0), None, Some(80.0));
        assert_eq!(c.len(), 1);
        assert_eq!(c[0], "lead");
    }

    #[test]
    fn unknown_chemistry_never_conflicts() {
        let c = recycled_content_chemistry_conflicts(
            "mystery",
            Some(5.0),
            Some(5.0),
            Some(5.0),
            Some(5.0),
        );
        assert!(c.is_empty());
    }
}