//! # Origin Escrow Contract — Template canonical Phase 3 Slice 3.3
//!
//! **Second foundational template** del Origin Contract Atelier. Multi-party
//! escrow + time-locked + dispute-enabled. Para commerce + freelance + institutional
//! partnerships donde necesitamos trust-minimized fund custody con resolution path.
//!
//! ## Use cases canonical
//!
//! 1. **Freelance contracts**: cliente deposita fondos → trabajo completado →
//!    fondos released a worker. Si disputa, Tribunal Pillar 6 decide.
//! 2. **Marketplace OMC purchases**: comprador deposita → vendedor delivers asset
//!    → fondos released. Refund posible si delivery falla con evidence.
//! 3. **Institutional partnerships**: universidad deposita fondos investigación →
//!    milestones met → progressive releases. Tribunal arbitra disputas.
//! 4. **Event tickets refundable**: organizer deposita garantía → evento ocurre →
//!    garantía released. Si event cancelado, refunds automáticos a holders.
//!
//! ## Inmutables honored
//!
//! - **#16 HTS anti-clasista**: escrow fee 1.5% canonical baseline + 5% max
//!   ceiling (BM V2 Pillar 6 §5.3 ratified). Pi 5 institutional escrows pueden
//!   subsidized rate via HardwareTier modulation Phase 3.x.
//! - **#26 Content-Addressed Immutability**: terms_hash BLAKE3 del contract terms
//!   inmutable post-deploy. Cualquier party puede verificar terms originales.
//! - **#37 Free perpetua**: reads (query_state, list_milestones, view_terms)
//!   gratis sin payment.
//! - **#41 AGI Cross-Species**: AGI accounts pueden ser party canonical (depositor,
//!   beneficiary, arbiter). Compile-detect via AccountId32 standard.
//!
//! ## Lifecycle canonical (5 states)
//!
//! ```
//! Created ──► Active ──► Releasing ──► Completed
//!    │           │           │
//!    │           ▼           ▼
//!    └────► Disputed ──► Tribunal ──► Resolved (Released | Refunded | Split)
//! ```
//!
//! - **Created**: contract deployed canonical, NO deposit yet
//! - **Active**: depositor funded canonical, awaiting milestones/conditions
//! - **Disputed**: party raised dispute canonical, frozen pending Tribunal
//! - **Releasing**: condition met canonical, automatic release initiated
//! - **Completed**: funds disbursed canonical, contract terminal state
//!
//! ## Policy-first parameters (Contract Atelier UI exposure)
//!
//! - `depositor`: AccountId del payer canonical
//! - `beneficiary`: AccountId del payee canonical
//! - `arbiter`: AccountId del Tribunal canonical (Pillar 6 Tribunal contract)
//! - `total_amount`: Balance escrowed canonical
//! - `milestones`: Vec<Milestone> canonical (amount + due_block + description_hash)
//! - `escrow_fee_bps`: u16 (default 150 = 1.5%, BM V2 baseline)
//! - `dispute_window_blocks`: u32 (window canonical para raise dispute post-release)
//! - `auto_release_blocks`: u32 (auto-release if no dispute canonical post-completion)
//! - `early_release_allowed`: bool (depositor pueda release early canonical)

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

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

    pub type MilestoneId = u32;
    pub type BasisPoints = u16;
    pub type TermsHash = [u8; 32];

    // ─────────────────────────────────────────────────────────────────
    // State machine canonical
    // ─────────────────────────────────────────────────────────────────

    #[derive(Debug, Clone, Copy, PartialEq, Eq, scale::Encode, scale::Decode)]
    #[cfg_attr(feature = "std", derive(scale_info::TypeInfo))]
    pub enum EscrowState {
        Created,
        Active,
        Disputed,
        Releasing,
        Completed,
    }

    /// Milestone canonical structure — define partial releases del total_amount.
    #[derive(Debug, Clone, scale::Encode, scale::Decode)]
    #[cfg_attr(feature = "std", derive(scale_info::TypeInfo))]
    pub struct Milestone {
        pub amount: Balance,
        pub due_block: BlockNumber,
        pub description_hash: TermsHash,
        pub completed: bool,
        pub completed_at: Option<BlockNumber>,
    }

    /// Resolution canonical del Tribunal post-dispute.
    #[derive(Debug, Clone, Copy, PartialEq, Eq, scale::Encode, scale::Decode)]
    #[cfg_attr(feature = "std", derive(scale_info::TypeInfo))]
    pub enum Resolution {
        ReleaseToBeneficiary,
        RefundToDepositor,
        SplitFifty,
        Custom { depositor_bps: BasisPoints, beneficiary_bps: BasisPoints },
    }

    // ─────────────────────────────────────────────────────────────────
    // Storage canonical
    // ─────────────────────────────────────────────────────────────────

    #[ink(storage)]
    pub struct OriginEscrow {
        // ── Parties + config ─────────────────────────────────────
        depositor: AccountId,
        beneficiary: AccountId,
        arbiter: AccountId,
        treasury: AccountId,
        terms_hash: TermsHash,
        total_amount: Balance,
        escrow_fee_bps: BasisPoints,
        dispute_window_blocks: BlockNumber,
        auto_release_blocks: BlockNumber,
        early_release_allowed: bool,

        // ── State ───────────────────────────────────────────────
        state: EscrowState,
        deposited_amount: Balance,
        released_amount: Balance,
        dispute_raised_at: Option<BlockNumber>,
        dispute_raised_by: Option<AccountId>,
        last_release_block: Option<BlockNumber>,

        // ── Milestones canonical (partial releases) ─────────────
        milestone_count: u32,
        milestones: Mapping<MilestoneId, Milestone>,
    }

    // ─────────────────────────────────────────────────────────────────
    // Events canonical
    // ─────────────────────────────────────────────────────────────────

    #[ink(event)]
    pub struct Deposited {
        #[ink(topic)]
        depositor: AccountId,
        amount: Balance,
    }

    #[ink(event)]
    pub struct MilestoneCompleted {
        #[ink(topic)]
        milestone_id: MilestoneId,
        amount_released: Balance,
    }

    #[ink(event)]
    pub struct DisputeRaised {
        #[ink(topic)]
        raised_by: AccountId,
        #[ink(topic)]
        arbiter: AccountId,
    }

    #[ink(event)]
    pub struct DisputeResolved {
        #[ink(topic)]
        arbiter: AccountId,
        resolution: Resolution,
        depositor_refund: Balance,
        beneficiary_release: Balance,
    }

    #[ink(event)]
    pub struct EscrowCompleted {
        total_released: Balance,
        total_refunded: Balance,
        treasury_fee: Balance,
    }

    // ─────────────────────────────────────────────────────────────────
    // Errors canonical
    // ─────────────────────────────────────────────────────────────────

    #[derive(Debug, PartialEq, Eq, scale::Encode, scale::Decode)]
    #[cfg_attr(feature = "std", derive(scale_info::TypeInfo))]
    pub enum Error {
        InvalidState,
        UnauthorizedCaller,
        InsufficientDeposit,
        MilestoneNotFound,
        MilestoneAlreadyCompleted,
        MilestoneNotDueYet,
        DisputeAlreadyRaised,
        DisputeWindowClosed,
        InvalidResolution,
        InvalidConfiguration,
        TransferFailed,
        EarlyReleaseProhibited,
    }

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

    impl OriginEscrow {
        /// Constructor canonical con full parameters.
        ///
        /// Invariant compile-detect: escrow_fee_bps ≤ 500 (5% max ceiling BM V2 §5.3).
        #[ink(constructor)]
        pub fn new(
            depositor: AccountId,
            beneficiary: AccountId,
            arbiter: AccountId,
            treasury: AccountId,
            terms_hash: TermsHash,
            total_amount: Balance,
            escrow_fee_bps: BasisPoints,
            dispute_window_blocks: BlockNumber,
            auto_release_blocks: BlockNumber,
            early_release_allowed: bool,
        ) -> core::result::Result<Self, Error> {
            if escrow_fee_bps > 500 {
                return Err(Error::InvalidConfiguration); // Max 5% canonical ceiling
            }
            if terms_hash == [0u8; 32] {
                return Err(Error::InvalidConfiguration);
            }
            if depositor == beneficiary {
                return Err(Error::InvalidConfiguration);
            }

            Ok(Self {
                depositor,
                beneficiary,
                arbiter,
                treasury,
                terms_hash,
                total_amount,
                escrow_fee_bps,
                dispute_window_blocks,
                auto_release_blocks,
                early_release_allowed,
                state: EscrowState::Created,
                deposited_amount: 0,
                released_amount: 0,
                dispute_raised_at: None,
                dispute_raised_by: None,
                last_release_block: None,
                milestone_count: 0,
                milestones: Mapping::default(),
            })
        }

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

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

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

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

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

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

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

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

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

        #[ink(message)]
        pub fn milestone(&self, id: MilestoneId) -> Option<Milestone> {
            self.milestones.get(id)
        }

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

        // ── Writes (state transitions) ──────────────────────────

        /// Deposit canonical — depositor funds the escrow.
        /// Transitions Created → Active canonical.
        #[ink(message, payable)]
        pub fn deposit(&mut self) -> Result<()> {
            if self.state != EscrowState::Created {
                return Err(Error::InvalidState);
            }
            if self.env().caller() != self.depositor {
                return Err(Error::UnauthorizedCaller);
            }
            let value = self.env().transferred_value();
            if value < self.total_amount {
                return Err(Error::InsufficientDeposit);
            }
            self.deposited_amount = value;
            self.state = EscrowState::Active;
            self.env().emit_event(Deposited {
                depositor: self.depositor,
                amount: value,
            });
            Ok(())
        }

        /// Add milestone canonical (depositor-only, pre-active state).
        /// Sum of milestone amounts MUST eventually equal total_amount.
        #[ink(message)]
        pub fn add_milestone(
            &mut self,
            amount: Balance,
            due_block: BlockNumber,
            description_hash: TermsHash,
        ) -> Result<MilestoneId> {
            if self.state != EscrowState::Created && self.state != EscrowState::Active {
                return Err(Error::InvalidState);
            }
            if self.env().caller() != self.depositor {
                return Err(Error::UnauthorizedCaller);
            }
            let id = self.milestone_count;
            self.milestones.insert(id, &Milestone {
                amount,
                due_block,
                description_hash,
                completed: false,
                completed_at: None,
            });
            self.milestone_count = self.milestone_count.saturating_add(1);
            Ok(id)
        }

        /// Confirm milestone completion canonical — releases milestone.amount al
        /// beneficiary minus escrow fee canonical.
        /// Callable canonical por depositor OR arbiter (depositor for satisfaction,
        /// arbiter for compelled release post-dispute).
        #[ink(message)]
        pub fn confirm_milestone(&mut self, milestone_id: MilestoneId) -> Result<()> {
            if self.state != EscrowState::Active {
                return Err(Error::InvalidState);
            }
            let caller = self.env().caller();
            if caller != self.depositor && caller != self.arbiter {
                return Err(Error::UnauthorizedCaller);
            }
            let mut milestone = self.milestones.get(milestone_id).ok_or(Error::MilestoneNotFound)?;
            if milestone.completed {
                return Err(Error::MilestoneAlreadyCompleted);
            }
            // Early release check canonical
            let now = self.env().block_number();
            if !self.early_release_allowed && now < milestone.due_block {
                return Err(Error::EarlyReleaseProhibited);
            }

            // Release canonical: amount - escrow_fee → beneficiary
            let fee = milestone.amount
                .saturating_mul(self.escrow_fee_bps as Balance)
                .saturating_div(10_000);
            let net = milestone.amount.saturating_sub(fee);

            self.env().transfer(self.beneficiary, net).map_err(|_| Error::TransferFailed)?;
            self.env().transfer(self.treasury, fee).map_err(|_| Error::TransferFailed)?;

            milestone.completed = true;
            milestone.completed_at = Some(now);
            self.milestones.insert(milestone_id, &milestone);

            self.released_amount = self.released_amount.saturating_add(milestone.amount);
            self.last_release_block = Some(now);

            self.env().emit_event(MilestoneCompleted {
                milestone_id,
                amount_released: net,
            });

            // Auto-transition Completed if all milestones canonical released
            if self.released_amount >= self.total_amount {
                self.state = EscrowState::Completed;
                self.env().emit_event(EscrowCompleted {
                    total_released: self.released_amount,
                    total_refunded: 0,
                    treasury_fee: fee,
                });
            }

            Ok(())
        }

        /// Raise dispute canonical — freezes escrow pending Tribunal resolution.
        /// Callable canonical por depositor OR beneficiary (any party).
        #[ink(message)]
        pub fn raise_dispute(&mut self) -> Result<()> {
            if self.state != EscrowState::Active {
                return Err(Error::InvalidState);
            }
            let caller = self.env().caller();
            if caller != self.depositor && caller != self.beneficiary {
                return Err(Error::UnauthorizedCaller);
            }
            if self.dispute_raised_at.is_some() {
                return Err(Error::DisputeAlreadyRaised);
            }
            self.state = EscrowState::Disputed;
            self.dispute_raised_at = Some(self.env().block_number());
            self.dispute_raised_by = Some(caller);
            self.env().emit_event(DisputeRaised {
                raised_by: caller,
                arbiter: self.arbiter,
            });
            Ok(())
        }

        /// Resolve dispute canonical — arbiter (Tribunal Pillar 6) decides.
        /// Transitions Disputed → Completed canonical.
        #[ink(message)]
        pub fn resolve_dispute(&mut self, resolution: Resolution) -> Result<()> {
            if self.state != EscrowState::Disputed {
                return Err(Error::InvalidState);
            }
            if self.env().caller() != self.arbiter {
                return Err(Error::UnauthorizedCaller);
            }

            let remaining = self.deposited_amount.saturating_sub(self.released_amount);
            let fee = remaining
                .saturating_mul(self.escrow_fee_bps as Balance)
                .saturating_div(10_000);
            let net_remaining = remaining.saturating_sub(fee);

            let (depositor_refund, beneficiary_release) = match resolution {
                Resolution::ReleaseToBeneficiary => (0, net_remaining),
                Resolution::RefundToDepositor => (net_remaining, 0),
                Resolution::SplitFifty => {
                    let half = net_remaining / 2;
                    (half, net_remaining.saturating_sub(half))
                }
                Resolution::Custom { depositor_bps, beneficiary_bps } => {
                    if depositor_bps.saturating_add(beneficiary_bps) != 10_000 {
                        return Err(Error::InvalidResolution);
                    }
                    let dep = net_remaining
                        .saturating_mul(depositor_bps as Balance)
                        .saturating_div(10_000);
                    (dep, net_remaining.saturating_sub(dep))
                }
            };

            if depositor_refund > 0 {
                self.env().transfer(self.depositor, depositor_refund).map_err(|_| Error::TransferFailed)?;
            }
            if beneficiary_release > 0 {
                self.env().transfer(self.beneficiary, beneficiary_release).map_err(|_| Error::TransferFailed)?;
            }
            self.env().transfer(self.treasury, fee).map_err(|_| Error::TransferFailed)?;

            self.state = EscrowState::Completed;
            self.env().emit_event(DisputeResolved {
                arbiter: self.arbiter,
                resolution,
                depositor_refund,
                beneficiary_release,
            });
            self.env().emit_event(EscrowCompleted {
                total_released: self.released_amount.saturating_add(beneficiary_release),
                total_refunded: depositor_refund,
                treasury_fee: fee,
            });

            Ok(())
        }
    }

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

        #[ink::test]
        fn constructor_canonical_invariants() {
            let result = OriginEscrow::new(
                AccountId::from([1u8; 32]),
                AccountId::from([2u8; 32]),
                AccountId::from([3u8; 32]),
                AccountId::from([4u8; 32]),
                [1u8; 32],
                1_000_000_000_000_000_000,
                150,  // 1.5% canonical BM V2
                100,
                1000,
                false,
            );
            assert!(result.is_ok());
            let escrow = result.unwrap();
            assert_eq!(escrow.state(), EscrowState::Created);
            assert_eq!(escrow.deposited_amount(), 0);
        }

        #[ink::test]
        fn excessive_fee_rejected_canonical() {
            let result = OriginEscrow::new(
                AccountId::from([1u8; 32]),
                AccountId::from([2u8; 32]),
                AccountId::from([3u8; 32]),
                AccountId::from([4u8; 32]),
                [1u8; 32],
                1_000_000_000_000_000_000,
                600,  // 6% — exceeds 5% max BM V2 ceiling
                100, 1000, false,
            );
            assert_eq!(result.err(), Some(Error::InvalidConfiguration));
        }

        #[ink::test]
        fn same_party_depositor_beneficiary_rejected() {
            let same = AccountId::from([1u8; 32]);
            let result = OriginEscrow::new(
                same, same,
                AccountId::from([3u8; 32]),
                AccountId::from([4u8; 32]),
                [1u8; 32],
                1_000_000_000_000_000_000,
                150, 100, 1000, false,
            );
            assert_eq!(result.err(), Some(Error::InvalidConfiguration));
        }
    }
}