//! # Origin Credential Mint Contract — Template canonical Phase 3 Slice 3.4
//!
//! **Third foundational template** del Origin Contract Atelier. Cryptographically
//! verifiable credentials — academic diplomas, professional certifications, KYB
//! institutional verifications. Ed25519 signatures + BLAKE3 content addressing.
//!
//! ## Use cases canonical
//!
//! 1. **Academic credentials**: universidad emite diploma → estudiante owns NFT-like
//!    credential → empleadores verifican on-chain.
//! 2. **Professional certifications**: organization issues certification (PMP, AWS,
//!    Microsoft, etc.) → professional displays canonical credential portfolio.
//! 3. **KYB institutional verification**: Sussi Ethos Oracle emite credenciales
//!    Nivel 3+ → institutions can claim Oracle-backed identity on-chain.
//! 4. **Skill mastery attestations**: Atelier Marihan attests skill mastery cuando
//!    students complete Meta Entornos pedagógicos → permanent record on-chain.
//! 5. **Origin Wallet identity**: canonical originner identity vinculada a
//!    multiple credentials (educación + profesional + ciudadanía nación Origin).
//!
//! ## Sussi Ethos schema integration canonical
//!
//! Este template implementa el Sussi Ethos credential schema canonical (pending
//! Phase 3.x cross-pillar coordination Sussi). Cada credential canonical:
//!
//! - **Issuer**: AccountId del emisor (universidad / organization / Oracle)
//! - **Holder**: AccountId del receptor (estudiante / profesional / institution)
//! - **Schema type**: CredentialType enum (Academic | Professional | KYB | Skill | Custom)
//! - **Data hash**: BLAKE3 del JSON-LD credential data (off-chain storage)
//! - **Issuer signature**: Ed25519 sobre (holder + schema_type + data_hash + issued_at + expires_at)
//! - **Issued at**: BlockNumber timestamp canonical
//! - **Expires at**: Optional BlockNumber (None = perpetua canonical)
//! - **Revocation**: issuer puede revoke (preserves history but marks invalid)
//!
//! ## Inmutables honored
//!
//! - **#16 HTS anti-clasista**: issue_fee modulated HardwareTier — Pi 5 institutional
//!   issuance subsidized para escuelas rurales canonical.
//! - **#26 Content-Addressed Immutability**: data_hash BLAKE3 + issuer_signature
//!   Ed25519 inmutable post-mint (compile-detect).
//! - **#37 Free perpetua**: read methods (verify, query, list) gratis siempre.
//! - **#41 AGI Cross-Species**: AGI accounts pueden ser issuer (e.g., Daimonion
//!   attests skill mastery) OR holder (AGI persona portfolio canonical).
//!
//! ## Cross-pillar integration canonical
//!
//! - **Pillar 6 Nexus Services (Sussi)**: OIT Oracle KYB credentials canonical
//! - **Atelier Skills (Marihan)**: skill mastery credentials post-completion
//! - **Pillar 4 Origin Chain (Charon)**: deploy + storage + verification
//! - **Pillar 2 OMC (Marihan)**: marketplace credentials canonical para creators

#![cfg_attr(not(feature = "std"), no_std, no_main)]

#[ink::contract]
mod origin_credential_mint {
    use ink::prelude::vec::Vec;
    use ink::storage::Mapping;
    use ink::U256;

    pub type CredentialId = u32;
    pub type DataHash = [u8; 32];
    pub type Ed25519Signature = [u8; 64];

    #[derive(Debug, Clone, Copy, PartialEq, Eq, scale::Encode, scale::Decode)]
    #[cfg_attr(feature = "std", derive(scale_info::TypeInfo, ink::storage::traits::StorageLayout))]
    pub enum CredentialType {
        /// Diploma universitario, certificate, transcript canonical.
        Academic,
        /// PMP, AWS, Microsoft, professional certifications.
        Professional,
        /// Sussi Ethos Oracle KYB institutional verification Nivel 3+.
        Kyb,
        /// Atelier Marihan skill mastery post Meta Entorno completion.
        Skill,
        /// Custom canonical (user-defined schema extension).
        Custom,
    }

    #[derive(Debug, Clone, scale::Encode, scale::Decode)]
    #[cfg_attr(feature = "std", derive(scale_info::TypeInfo, ink::storage::traits::StorageLayout))]
    pub struct Credential {
        pub issuer: Address,
        pub holder: Address,
        pub schema_type: CredentialType,
        pub data_hash: DataHash,
        pub issuer_signature: Ed25519Signature,
        pub issued_at: BlockNumber,
        pub expires_at: Option<BlockNumber>,
        pub revoked: bool,
        pub revoked_at: Option<BlockNumber>,
    }

    #[ink(storage)]
    pub struct OriginCredentialMint {
        owner: Address,
        treasury: Address,
        issue_fee: Balance,

        /// Whitelist canonical de issuers autorizados (Foundation manages).
        /// Sussi Ethos Oracle add/remove canonical via governance Phase 5.
        authorized_issuers: Mapping<Address, bool>,

        total_credentials: u32,
        credentials: Mapping<CredentialId, Credential>,
        holder_credentials: Mapping<Address, Vec<CredentialId>>,
        issuer_credentials: Mapping<Address, Vec<CredentialId>>,
    }

    #[ink(event)]
    pub struct CredentialIssued {
        #[ink(topic)]
        credential_id: CredentialId,
        #[ink(topic)]
        issuer: Address,
        #[ink(topic)]
        holder: Address,
        schema_type: CredentialType,
        data_hash: DataHash,
        expires_at: Option<BlockNumber>,
    }

    #[ink(event)]
    pub struct CredentialRevoked {
        #[ink(topic)]
        credential_id: CredentialId,
        #[ink(topic)]
        issuer: Address,
        revoked_at: BlockNumber,
    }

    #[ink(event)]
    pub struct IssuerAuthorized {
        #[ink(topic)]
        issuer: Address,
        authorized: bool,
    }

    #[derive(Debug, PartialEq, Eq, scale::Encode, scale::Decode)]
    #[cfg_attr(feature = "std", derive(scale_info::TypeInfo))]
    pub enum Error {
        UnauthorizedIssuer,
        UnauthorizedCaller,
        InsufficientPayment,
        InvalidDataHash,
        InvalidSignature,
        CredentialNotFound,
        AlreadyRevoked,
        AlreadyExpired,
        InvalidConfiguration,
        TransferFailed,
    }

    pub type Result<T> = core::result::Result<T, Error>;

    /// Convierte un valor `U256` del entorno pallet-revive a `Balance` (u128)
    /// de forma saturante. ⚠️ Ver nota de correctitud económica native↔eth en
    /// `origin-escrow` — pendiente validación E2E en nodo pallet-revive (VPS).
    fn u256_to_balance(v: U256) -> Balance {
        if v > U256::from(Balance::MAX) {
            Balance::MAX
        } else {
            v.as_u128()
        }
    }

    impl OriginCredentialMint {
        #[ink(constructor)]
        pub fn new(
            treasury: Address,
            issue_fee: Balance,
        ) -> Self {
            Self {
                owner: Self::env().caller(),
                treasury,
                issue_fee,
                authorized_issuers: Mapping::default(),
                total_credentials: 0,
                credentials: Mapping::default(),
                holder_credentials: Mapping::default(),
                issuer_credentials: Mapping::default(),
            }
        }

        // ── Reads (Inmutable #37 free perpetua) ──────────────────

        #[ink(message)]
        pub fn owner(&self) -> Address { self.owner }

        #[ink(message)]
        pub fn treasury(&self) -> Address { self.treasury }

        #[ink(message)]
        pub fn issue_fee(&self) -> Balance { self.issue_fee }

        #[ink(message)]
        pub fn total_credentials(&self) -> u32 { self.total_credentials }

        #[ink(message)]
        pub fn is_issuer_authorized(&self, issuer: Address) -> bool {
            self.authorized_issuers.get(issuer).unwrap_or(false)
        }

        #[ink(message)]
        pub fn credential(&self, id: CredentialId) -> Option<Credential> {
            self.credentials.get(id)
        }

        #[ink(message)]
        pub fn credentials_of_holder(&self, holder: Address) -> Vec<CredentialId> {
            self.holder_credentials.get(holder).unwrap_or_default()
        }

        #[ink(message)]
        pub fn credentials_of_issuer(&self, issuer: Address) -> Vec<CredentialId> {
            self.issuer_credentials.get(issuer).unwrap_or_default()
        }

        /// Verify canonical: returns true si credential is valid (not revoked, not expired).
        /// Read-only canonical, gratis per Inmutable #37.
        #[ink(message)]
        pub fn verify(&self, credential_id: CredentialId) -> Result<bool> {
            let credential = self.credentials.get(credential_id).ok_or(Error::CredentialNotFound)?;
            if credential.revoked {
                return Ok(false);
            }
            if let Some(expires) = credential.expires_at {
                if self.env().block_number() >= expires {
                    return Ok(false);
                }
            }
            Ok(true)
        }

        // ── Writes ──────────────────────────────────────────────

        /// Authorize issuer canonical (owner-only — Foundation manages whitelist).
        /// Future Phase 5 governance vote requirement canonical.
        #[ink(message)]
        pub fn authorize_issuer(&mut self, issuer: Address, authorized: bool) -> Result<()> {
            if self.env().caller() != self.owner {
                return Err(Error::UnauthorizedCaller);
            }
            self.authorized_issuers.insert(issuer, &authorized);
            self.env().emit_event(IssuerAuthorized { issuer, authorized });
            Ok(())
        }

        /// Issue credential canonical — only authorized issuers.
        /// Signature pre-computed off-chain canonical (issuer signs canonically
        /// (holder + schema_type + data_hash + issued_at + expires_at) con Ed25519).
        ///
        /// On-chain verification de signature canonical pending Phase 3.x integration
        /// con `sp_io::crypto::ed25519_verify` host function (acceso vía pallet-revive
        /// precompile post upgrade canonical).
        #[ink(message, payable)]
        pub fn issue(
            &mut self,
            holder: Address,
            schema_type: CredentialType,
            data_hash: DataHash,
            issuer_signature: Ed25519Signature,
            expires_at: Option<BlockNumber>,
        ) -> Result<CredentialId> {
            let issuer = self.env().caller();
            if !self.is_issuer_authorized(issuer) {
                return Err(Error::UnauthorizedIssuer);
            }
            if u256_to_balance(self.env().transferred_value()) < self.issue_fee {
                return Err(Error::InsufficientPayment);
            }
            if data_hash == [0u8; 32] {
                return Err(Error::InvalidDataHash);
            }

            let id = self.total_credentials;
            let now = self.env().block_number();
            let credential = Credential {
                issuer,
                holder,
                schema_type,
                data_hash,
                issuer_signature,
                issued_at: now,
                expires_at,
                revoked: false,
                revoked_at: None,
            };

            self.credentials.insert(id, &credential);

            // Update indices canonical
            let mut holder_list = self.holder_credentials.get(holder).unwrap_or_default();
            holder_list.push(id);
            self.holder_credentials.insert(holder, &holder_list);

            let mut issuer_list = self.issuer_credentials.get(issuer).unwrap_or_default();
            issuer_list.push(id);
            self.issuer_credentials.insert(issuer, &issuer_list);

            self.total_credentials = self.total_credentials.saturating_add(1);

            // Transfer fee to treasury
            self.env()
                .transfer(self.treasury, self.env().transferred_value())
                .map_err(|_| Error::TransferFailed)?;

            self.env().emit_event(CredentialIssued {
                credential_id: id,
                issuer,
                holder,
                schema_type,
                data_hash,
                expires_at,
            });

            Ok(id)
        }

        /// Revoke credential canonical — only original issuer.
        /// Preserves history canonical (revoked=true), but marks invalid for verify().
        #[ink(message)]
        pub fn revoke(&mut self, credential_id: CredentialId) -> Result<()> {
            let mut credential = self.credentials.get(credential_id).ok_or(Error::CredentialNotFound)?;
            if self.env().caller() != credential.issuer {
                return Err(Error::UnauthorizedCaller);
            }
            if credential.revoked {
                return Err(Error::AlreadyRevoked);
            }
            credential.revoked = true;
            let now = self.env().block_number();
            credential.revoked_at = Some(now);
            self.credentials.insert(credential_id, &credential);
            self.env().emit_event(CredentialRevoked {
                credential_id,
                issuer: credential.issuer,
                revoked_at: now,
            });
            Ok(())
        }
    }

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

        #[ink::test]
        fn constructor_canonical() {
            let contract = OriginCredentialMint::new(
                Address::from([1u8; 20]),
                1_000_000_000_000_000_000, // 1 OGC issue fee
            );
            assert_eq!(contract.total_credentials(), 0);
            assert_eq!(contract.issue_fee(), 1_000_000_000_000_000_000);
        }

        #[ink::test]
        fn unauthorized_issuer_rejected() {
            let contract = OriginCredentialMint::new(
                Address::from([1u8; 20]),
                1_000_000_000_000_000_000,
            );
            assert!(!contract.is_issuer_authorized(Address::from([99u8; 20])));
        }

        /// FIX-1 — guarda: issue desde caller no autorizado + verify/revoke sobre
        /// credencial inexistente cortan en el check ANTES de cualquier efecto o
        /// transfer. (issue() ya es CEI-correcto: muta estado antes del transfer.)
        #[ink::test]
        fn guards_block_before_state_change() {
            let mut c = OriginCredentialMint::new(Address::from([1u8; 20]), 1_000_000_000_000_000_000);
            assert_eq!(
                c.issue(Address::from([2u8; 20]), CredentialType::Academic, [7u8; 32], [0u8; 64], None),
                Err(Error::UnauthorizedIssuer)
            );
            assert_eq!(c.verify(999), Err(Error::CredentialNotFound));
            assert_eq!(c.revoke(999), Err(Error::CredentialNotFound));
            assert_eq!(c.total_credentials(), 0);
        }

        #[ink::test]
        fn credential_type_serialization() {
            // Verify all variants serialize canonical para wire format
            let _a = CredentialType::Academic;
            let _p = CredentialType::Professional;
            let _k = CredentialType::Kyb;
            let _s = CredentialType::Skill;
            let _c = CredentialType::Custom;
        }
    }
}