use remora_stream::{StreamError, StreamSide};

/// Target storage adapter errors.
///
/// Diagnostic text is for operator logs only after secret scrubbing. Public
/// projections go through [`remora_stream::classify_stream_error`].
#[derive(Debug, thiserror::Error)]
pub enum TargetError {
    #[error("target authorization failure")]
    Authorization,
    #[error("object already exists under create-only identity")]
    AlreadyExists,
    #[error("object not found")]
    NotFound,
    #[error("integrity failure: {0}")]
    Integrity(String),
    #[error("capacity exhausted on target")]
    Capacity,
    #[error("transient target failure: {0}")]
    Transient(String),
    #[error("validation failure: {0}")]
    Validation(String),
    #[error("internal target error: {0}")]
    Internal(String),
}

impl TargetError {
    pub fn validation(detail: impl Into<String>) -> Self {
        Self::Validation(detail.into())
    }

    pub fn integrity(detail: impl Into<String>) -> Self {
        Self::Integrity(detail.into())
    }

    pub fn transient(detail: impl Into<String>) -> Self {
        Self::Transient(detail.into())
    }

    pub fn internal(detail: impl Into<String>) -> Self {
        Self::Internal(detail.into())
    }

    /// Map to a stream error for copy-loop and adapter I/O boundaries.
    #[must_use]
    pub fn into_stream_error(self) -> StreamError {
        match self {
            Self::Authorization => StreamError::Authorization {
                side: StreamSide::Target,
            },
            Self::AlreadyExists => StreamError::integrity("create-only identity already exists"),
            Self::NotFound => StreamError::internal("target object not found"),
            Self::Integrity(detail) => StreamError::Integrity { detail },
            Self::Capacity => StreamError::Capacity {
                side: StreamSide::Target,
            },
            Self::Transient(detail) => StreamError::Transient {
                side: StreamSide::Target,
                detail,
            },
            Self::Validation(detail) => StreamError::internal(detail),
            Self::Internal(detail) => StreamError::Internal { detail },
        }
    }
}

impl From<TargetError> for StreamError {
    fn from(value: TargetError) -> Self {
        value.into_stream_error()
    }
}

/// Map OpenDAL errors without embedding raw exception bodies in public paths.
pub(crate) fn map_opendal(error: opendal::Error) -> TargetError {
    use opendal::ErrorKind;

    let detail = redact_sensitive(error.to_string());
    match error.kind() {
        ErrorKind::NotFound => TargetError::NotFound,
        ErrorKind::PermissionDenied => TargetError::Authorization,
        ErrorKind::AlreadyExists | ErrorKind::ConditionNotMatch => TargetError::AlreadyExists,
        ErrorKind::RateLimited => TargetError::Capacity,
        ErrorKind::Unsupported | ErrorKind::ConfigInvalid => TargetError::Validation(detail),
        ErrorKind::Unexpected
        | ErrorKind::IsADirectory
        | ErrorKind::NotADirectory
        | ErrorKind::IsSameFile
        | ErrorKind::RangeNotSatisfied => {
            if is_likely_transient(&detail) {
                TargetError::Transient(detail)
            } else {
                TargetError::Internal(detail)
            }
        }
        _ => TargetError::Internal(detail),
    }
}

pub(crate) fn map_http_status(status: u16, body: &str) -> TargetError {
    let detail = redact_sensitive(body);
    match status {
        401 | 403 => TargetError::Authorization,
        404 => TargetError::NotFound,
        409 | 412 => TargetError::AlreadyExists,
        429 | 503 => TargetError::Capacity,
        500 | 502 | 504 => TargetError::Transient(format!("http {status}: {detail}")),
        _ if status >= 500 => TargetError::Transient(format!("http {status}: {detail}")),
        _ => TargetError::Internal(format!("http {status}: {detail}")),
    }
}

/// Scrub credential-bearing fragments from operator-facing diagnostic text.
pub(crate) fn redact_sensitive(input: impl AsRef<str>) -> String {
    let mut out = input.as_ref().to_owned();
    const NEEDLES: &[&str] = &[
        "Authorization:",
        "authorization:",
        "AWSAccessKeyId=",
        "X-Amz-Credential=",
        "X-Amz-Signature=",
        "X-Amz-Security-Token=",
        "x-amz-security-token=",
        "Credential=",
        "Signature=",
        "SecretAccessKey",
        "secret_access_key",
        "secret-access-key",
        "Bearer ",
    ];
    while let Some((idx, needle)) = NEEDLES
        .iter()
        .filter_map(|needle| out.find(needle).map(|idx| (idx, *needle)))
        .min_by_key(|(idx, _)| *idx)
    {
        let value_start = idx + needle.len();
        // Authorization headers are multi-token; scrub through end of line.
        let value_end = if needle.eq_ignore_ascii_case("Authorization:") {
            out[value_start..]
                .find(['\r', '\n'])
                .map(|offset| value_start + offset)
                .unwrap_or(out.len())
        } else {
            out[value_start..]
                .find(|character: char| {
                    character.is_whitespace()
                        || matches!(character, '"' | '\'' | ',' | ';' | '&' | '<' | '>')
                })
                .map(|offset| value_start + offset)
                .unwrap_or(out.len())
        };
        out.replace_range(idx..value_end, "[redacted]");
    }
    if out.len() > 512 {
        out.truncate(512);
        out.push('…');
    }
    out
}

fn is_likely_transient(detail: &str) -> bool {
    let lower = detail.to_ascii_lowercase();
    lower.contains("timeout")
        || lower.contains("temporar")
        || lower.contains("connection")
        || lower.contains("reset")
        || lower.contains("unavailable")
        || lower.contains("slow down")
}

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

    #[test]
    fn redact_sensitive_scrubs_long_and_repeated_secrets() {
        let long_sig = "a".repeat(80);
        let input = format!(
            "X-Amz-Signature={long_sig}&X-Amz-Credential=AKIAEXAMPLE/path Authorization: AWS4-HMAC-SHA256 Credential=AKIAEXAMPLE, SignedHeaders=host, Signature={long_sig} Bearer super-secret-token-value-here"
        );
        let redacted = redact_sensitive(input);
        assert!(!redacted.contains("AKIAEXAMPLE"));
        assert!(!redacted.contains(&long_sig));
        assert!(!redacted.contains("super-secret-token-value-here"));
        assert!(redacted.contains("[redacted]"));
    }
}