package blockchain

import (
	"fmt"
)

// DeploymentError identifies an error that indicates a deployment ID was specified that does not exist.
type DeploymentError uint32

// Error returns the assertion error as a human-readable string and satisfies the error interface.
func (e DeploymentError) Error() string {
	return fmt.Sprintf("deployment ID %d does not exist", uint32(e))
}

// AssertError identifies an error that indicates an internal code consistency issue and should be treated as a critical
// and unrecoverable error.
type AssertError string

// Error returns the assertion error as a human-readable string and satisfies the error interface.
func (e AssertError) Error() string {
	return "assertion failed: " + string(e)
}

// ErrorCode identifies a kind of error.
type ErrorCode int

// These constants are used to identify a specific RuleError.
const (
	// ErrDuplicateBlock indicates a block with the same hash already exists.
	ErrDuplicateBlock ErrorCode = iota
	// ErrBlockTooBig indicates the serialized block size exceeds the maximum allowed size.
	ErrBlockTooBig
	// ErrBlockWeightTooHigh indicates that the block's computed weight metric exceeds the maximum allowed value.
	ErrBlockWeightTooHigh
	// ErrBlockVersionTooOld indicates the block version is too old and is no longer accepted since the majority of the
	// network has upgraded to a newer version.
	ErrBlockVersionTooOld
	// ErrInvalidTime indicates the time in the passed block has a precision that is more than one second. The chain
	// consensus rules require timestamps to have a maximum precision of one second.
	ErrInvalidTime
	// ErrTimeTooOld indicates the time is either before the median time of the last several blocks per the chain
	// consensus rules or prior to the most recent checkpoint.
	ErrTimeTooOld
	// ErrTimeTooNew indicates the time is too far in the future as compared the current time.
	ErrTimeTooNew
	// ErrDifficultyTooLow indicates the difficulty for the block is lower than the difficulty required by the most
	// recent checkpoint.
	ErrDifficultyTooLow
	// ErrUnexpectedDifficulty indicates specified bits do not align with the expected value either because it doesn't
	// match the calculated valued based on difficulty regarted rules or it is out of the valid range.
	ErrUnexpectedDifficulty
	// ErrHighHash indicates the block does not hash to a value which is lower than the required target difficultly.
	ErrHighHash
	// ErrBadMerkleRoot indicates the calculated merkle root does not match the expected value.
	ErrBadMerkleRoot
	// ErrBadCheckpoint indicates a block that is expected to be at a checkpoint height does not match the expected one.
	ErrBadCheckpoint
	// ErrForkTooOld indicates a block is attempting to fork the block chain before the most recent checkpoint.
	ErrForkTooOld
	// ErrCheckpointTimeTooOld indicates a block has a timestamp before the most recent checkpoint.
	ErrCheckpointTimeTooOld
	// ErrNoTransactions indicates the block does not have a least one transaction. A valid block must have at least the
	// coinbase transaction.
	ErrNoTransactions
	// ErrNoTxInputs indicates a transaction does not have any inputs. A valid transaction must have at least one input.
	ErrNoTxInputs
	// ErrNoTxOutputs indicates a transaction does not have any outputs. A valid transaction must have at least one
	// output.
	ErrNoTxOutputs
	// ErrTxTooBig indicates a transaction exceeds the maximum allowed size when serialized.
	ErrTxTooBig
	// ErrBadTxOutValue indicates an output value for a transaction is invalid in some way such as being out of range.
	ErrBadTxOutValue
	// ErrDuplicateTxInputs indicates a transaction references the same input more than once.
	ErrDuplicateTxInputs
	// ErrBadTxInput indicates a transaction input is invalid in some way such as referencing a previous transaction
	// outpoint which is out of range or not referencing one at all.
	ErrBadTxInput
	// ErrMissingTxOut indicates a transaction output referenced by an input either does not exist or has already been
	// spent.
	ErrMissingTxOut
	// ErrUnfinalizedTx indicates a transaction has not been finalized. A valid block may only contain finalized
	// transactions.
	ErrUnfinalizedTx
	// ErrDuplicateTx indicates a block contains an identical transaction (or at least two transactions which hash to
	// the same value). A valid block may only contain unique transactions.
	ErrDuplicateTx
	// ErrOverwriteTx indicates a block contains a transaction that has the same hash as a previous transaction which
	// has not been fully spent.
	ErrOverwriteTx
	// ErrImmatureSpend indicates a transaction is attempting to spend a coinbase that has not yet reached the required
	// maturity.
	ErrImmatureSpend
	// ErrSpendTooHigh indicates a transaction is attempting to spend more value than the sum of all of its inputs.
	ErrSpendTooHigh
	// ErrBadFees indicates the total fees for a block are invalid due to exceeding the maximum possible value.
	ErrBadFees
	// ErrTooManySigOps indicates the total number of signature operations for a transaction or block exceed the maximum
	// allowed limits.
	ErrTooManySigOps
	// ErrFirstTxNotCoinbase indicates the first transaction in a block is not a coinbase transaction.
	ErrFirstTxNotCoinbase
	// ErrMultipleCoinbases indicates a block contains more than one coinbase transaction.
	ErrMultipleCoinbases
	// ErrBadCoinbaseScriptLen indicates the length of the signature script for a coinbase transaction is not within the
	// valid range.
	ErrBadCoinbaseScriptLen
	// ErrBadCoinbaseValue indicates the amount of a coinbase value does not match the expected value of the subsidy
	// plus the sum of all fees.
	ErrBadCoinbaseValue
	// ErrMissingCoinbaseHeight indicates the coinbase transaction for a block does not start with the serialized block
	// block height as required for version 2 and higher blocks.
	ErrMissingCoinbaseHeight
	// ErrBadCoinbaseHeight indicates the serialized block height in the coinbase transaction for version 2 and higher
	// blocks does not match the expected value.
	ErrBadCoinbaseHeight
	// ErrScriptMalformed indicates a transaction script is malformed in some way. For example, it might be longer than
	// the maximum allowed length or fail to parse.
	ErrScriptMalformed
	// ErrScriptValidation indicates the result of executing transaction script failed. The error covers any failure
	// when executing scripts such signature verification failures and execution past the end of the stack.
	ErrScriptValidation
	// ErrUnexpectedWitness indicates that a block includes transactions with witness data, but doesn't also have a
	// witness commitment within the coinbase transaction.
	ErrUnexpectedWitness
	// ErrInvalidWitnessCommitment indicates that a block's witness commitment is not well formed.
	ErrInvalidWitnessCommitment
	// ErrWitnessCommitmentMismatch indicates that the witness commitment included in the block's coinbase transaction
	// doesn't match the manually computed witness commitment.
	ErrWitnessCommitmentMismatch
	// ErrPreviousBlockUnknown indicates that the previous block is not known.
	ErrPreviousBlockUnknown
	// ErrInvalidAncestorBlock indicates that an ancestor of this block has already failed validation.
	ErrInvalidAncestorBlock
	// ErrPrevBlockNotBest indicates that the block's previous block is not the current chain tip. This is not a block
	// validation rule, but is required for block proposals submitted via getblocktemplate RPC.
	ErrPrevBlockNotBest
	// ErrBlacklisted indicates a transaction contains a blacklisted address
	ErrBlacklisted
)

// Map of ErrorCode values back to their constant names for pretty printing.
var errorCodeStrings = map[ErrorCode]string{
	ErrDuplicateBlock:            "ErrDuplicateBlock",
	ErrBlockTooBig:               "ErrBlockTooBig",
	ErrBlockVersionTooOld:        "ErrBlockVersionTooOld",
	ErrBlockWeightTooHigh:        "ErrBlockWeightTooHigh",
	ErrInvalidTime:               "ErrInvalidTime",
	ErrTimeTooOld:                "ErrTimeTooOld",
	ErrTimeTooNew:                "ErrTimeTooNew",
	ErrDifficultyTooLow:          "ErrDifficultyTooLow",
	ErrUnexpectedDifficulty:      "ErrUnexpectedDifficulty",
	ErrHighHash:                  "ErrHighHash",
	ErrBadMerkleRoot:             "ErrBadMerkleRoot",
	ErrBadCheckpoint:             "ErrBadCheckpoint",
	ErrForkTooOld:                "ErrForkTooOld",
	ErrCheckpointTimeTooOld:      "ErrCheckpointTimeTooOld",
	ErrNoTransactions:            "ErrNoTransactions",
	ErrNoTxInputs:                "ErrNoTxInputs",
	ErrNoTxOutputs:               "ErrNoTxOutputs",
	ErrTxTooBig:                  "ErrTxTooBig",
	ErrBadTxOutValue:             "ErrBadTxOutValue",
	ErrDuplicateTxInputs:         "ErrDuplicateTxInputs",
	ErrBadTxInput:                "ErrBadTxInput",
	ErrMissingTxOut:              "ErrMissingTxOut",
	ErrUnfinalizedTx:             "ErrUnfinalizedTx",
	ErrDuplicateTx:               "ErrDuplicateTx",
	ErrOverwriteTx:               "ErrOverwriteTx",
	ErrImmatureSpend:             "ErrImmatureSpend",
	ErrSpendTooHigh:              "ErrSpendTooHigh",
	ErrBadFees:                   "ErrBadFees",
	ErrTooManySigOps:             "ErrTooManySigOps",
	ErrFirstTxNotCoinbase:        "ErrFirstTxNotCoinbase",
	ErrMultipleCoinbases:         "ErrMultipleCoinbases",
	ErrBadCoinbaseScriptLen:      "ErrBadCoinbaseScriptLen",
	ErrBadCoinbaseValue:          "ErrBadCoinbaseValue",
	ErrMissingCoinbaseHeight:     "ErrMissingCoinbaseHeight",
	ErrBadCoinbaseHeight:         "ErrBadCoinbaseHeight",
	ErrScriptMalformed:           "ErrScriptMalformed",
	ErrScriptValidation:          "ErrScriptValidation",
	ErrUnexpectedWitness:         "ErrUnexpectedWitness",
	ErrInvalidWitnessCommitment:  "ErrInvalidWitnessCommitment",
	ErrWitnessCommitmentMismatch: "ErrWitnessCommitmentMismatch",
	ErrPreviousBlockUnknown:      "ErrPreviousBlockUnknown",
	ErrInvalidAncestorBlock:      "ErrInvalidAncestorBlock",
	ErrPrevBlockNotBest:          "ErrPrevBlockNotBest",
}

// String returns the ErrorCode as a human-readable name.
func (e ErrorCode) String() string {
	if s := errorCodeStrings[e]; s != "" {
		return s
	}
	return fmt.Sprintf("Unknown ErrorCode (%d)", int(e))
}

// RuleError identifies a rule violation. It is used to indicate that processing of a block or transaction failed due to
// one of the many validation rules. The caller can use type assertions to determine if a failure was specifically due
// to a rule violation and access the ErrorCode field to ascertain the specific reason for the rule violation.
type RuleError struct {
	ErrorCode   ErrorCode // Describes the kind of error
	Description string    // Human readable description of the issue
}

// Error satisfies the error interface and prints human-readable errors.
func (e RuleError) Error() string {
	return e.Description
}

// ruleError creates an RuleError given a set of arguments.
func ruleError(c ErrorCode, desc string) RuleError {
	return RuleError{ErrorCode: c, Description: desc}
}