// SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
// SPDX-License-Identifier: Apache-2.0

//! Build container images for sandbox runtimes.
//!
//! This module wraps bollard's `build_image()` API to build a container image
//! from a Dockerfile and build context. Package-managed local gateways use the
//! host Docker daemon, so the resulting tag is passed to the gateway directly.

use std::collections::HashMap;
use std::path::Path;
use std::time::Duration;

use bollard::Docker;
use bollard::query_parameters::BuildImageOptionsBuilder;
use futures::StreamExt;
use miette::{IntoDiagnostic, Result, WrapErr};
use tokio::time::timeout;

/// Maximum gap between Docker build stream events before a build is treated
/// as stuck.
///
/// Total silence longer than this on under-provisioned container runtimes
/// (e.g. default Colima 2 vCPU / 2 GiB on macOS) reliably indicates a
/// deadlocked builder that will never recover. The default leaves headroom
/// for legitimately quiet steps (a single long `RUN` that produces no output)
/// — override with `OPENSHELL_BUILD_NO_PROGRESS_TIMEOUT_SECS` if a specific
/// build needs more time, or shorter for CI tightening.
const DEFAULT_BUILD_NO_PROGRESS_TIMEOUT_SECS: u64 = 1800;

async fn docker_daemon_platform(docker: &Docker) -> Result<String> {
    let info = docker
        .info()
        .await
        .into_diagnostic()
        .wrap_err("failed to query local Docker daemon info")?;
    let os = info
        .os_type
        .as_deref()
        .filter(|value| !value.is_empty())
        .ok_or_else(|| miette::miette!("Docker daemon did not report an operating system"))?;
    let arch = info
        .architecture
        .as_deref()
        .filter(|value| !value.is_empty())
        .ok_or_else(|| miette::miette!("Docker daemon did not report an architecture"))?;

    normalize_docker_platform(os, arch)
}

fn normalize_docker_platform(os: &str, arch: &str) -> Result<String> {
    // Remote or non-standard daemons may return mixed-case arch strings.
    let arch_lower = arch.to_lowercase();
    let normalized_arch = match arch_lower.as_str() {
        "amd64" | "x86_64" => "amd64",
        "arm64" | "aarch64" => "arm64",
        "arm" | "armv7" | "armv7l" | "armhf" => "arm/v7",
        "armv6" | "armv6l" => "arm/v6",
        "386" | "i386" | "i686" => "386",
        "ppc64le" => "ppc64le",
        "s390x" => "s390x",
        _ => {
            return Err(miette::miette!(
                "unsupported Docker daemon architecture for local image build: {arch}"
            ));
        }
    };
    Ok(format!("{os}/{normalized_arch}"))
}

/// Parse `os/arch[/variant]` and reject malformed empty segments.
fn parse_platform(platform: &str) -> Result<(&str, &str, &str)> {
    let mut parts = platform.split('/');
    let os = parts
        .next()
        .filter(|v| !v.is_empty())
        .ok_or_else(|| miette::miette!("platform is missing an operating system"))?;
    let arch = parts
        .next()
        .filter(|v| !v.is_empty())
        .ok_or_else(|| miette::miette!("platform is missing an architecture"))?;
    // A trailing slash creates a malformed empty variant segment.
    let variant = match parts.next() {
        Some("") => {
            return Err(miette::miette!(
                "platform variant must not be empty (trailing slash?): '{platform}'"
            ));
        }
        Some(v) => v,
        None => "",
    };
    if parts.next().is_some() {
        return Err(miette::miette!(
            "platform must be os/arch[/variant], got '{platform}'"
        ));
    }
    Ok((os, arch, variant))
}

/// Seed Docker's implicit `BuildKit` platform args without replacing caller values.
///
/// `target_platform` identifies the output image. `build_platform` identifies
/// the Docker daemon doing the build. Variant args are only injected when the
/// platform string has an explicit variant, which preserves Dockerfile ARG
/// defaults for no-variant platforms.
fn insert_implicit_platform_build_args(
    build_args: &mut HashMap<String, String>,
    target_platform: &str,
    build_platform: &str,
) -> Result<()> {
    let (target_os, target_arch, target_variant) = parse_platform(target_platform)
        .wrap_err_with(|| format!("invalid target platform '{target_platform}'"))?;
    let (build_os, build_arch, build_variant) = parse_platform(build_platform)
        .wrap_err_with(|| format!("invalid build platform '{build_platform}'"))?;

    for (key, val) in [
        ("TARGETPLATFORM", target_platform),
        ("TARGETOS", target_os),
        ("TARGETARCH", target_arch),
        ("BUILDPLATFORM", build_platform),
        ("BUILDOS", build_os),
        ("BUILDARCH", build_arch),
    ] {
        build_args
            .entry(key.to_string())
            .or_insert_with(|| val.to_string());
    }
    if !target_variant.is_empty() {
        build_args
            .entry("TARGETVARIANT".to_string())
            .or_insert_with(|| target_variant.to_string());
    }
    if !build_variant.is_empty() {
        build_args
            .entry("BUILDVARIANT".to_string())
            .or_insert_with(|| build_variant.to_string());
    }

    Ok(())
}

/// Build a container image from a Dockerfile using the local Docker daemon.
///
/// This is used by `openshell sandbox create --from <Dockerfile>`. The image
/// remains available in the local Docker daemon so the gateway's active local
/// compute driver can resolve the tag.
#[allow(clippy::implicit_hasher)]
pub async fn build_local_image(
    dockerfile_path: &Path,
    tag: &str,
    context_dir: &Path,
    build_args: &HashMap<String, String>,
    on_log: &mut impl FnMut(String),
) -> Result<()> {
    on_log(format!(
        "Building image {tag} from {}",
        dockerfile_path.display()
    ));
    build_image(dockerfile_path, tag, context_dir, build_args, on_log).await?;
    on_log(format!("Built image {tag}"));
    Ok(())
}

/// Build a container image using the local Docker daemon.
///
/// Creates a tar archive of `context_dir`, sends it to Docker with the
/// specified Dockerfile path and tag, and streams build output to `on_log`.
async fn build_image(
    dockerfile_path: &Path,
    tag: &str,
    context_dir: &Path,
    build_args: &HashMap<String, String>,
    on_log: &mut impl FnMut(String),
) -> Result<()> {
    let docker = Docker::connect_with_local_defaults()
        .into_diagnostic()
        .wrap_err("failed to connect to local Docker daemon")?;
    // BUILD* always comes from daemon info. A TARGETPLATFORM override only
    // changes the output image platform.
    let build_platform = docker_daemon_platform(&docker).await?;
    let target_platform = build_args
        .get("TARGETPLATFORM")
        .map_or_else(|| build_platform.clone(), Clone::clone);
    let mut effective_build_args = build_args.clone();
    insert_implicit_platform_build_args(
        &mut effective_build_args,
        &target_platform,
        &build_platform,
    )?;

    // Compute the relative path of the Dockerfile within the context.
    let dockerfile_relative = dockerfile_path
        .strip_prefix(context_dir)
        .unwrap_or(dockerfile_path);
    let dockerfile_str = dockerfile_relative
        .to_str()
        .ok_or_else(|| miette::miette!("Dockerfile path is not valid UTF-8"))?;

    // Create a tar archive of the build context, respecting .dockerignore.
    let context_tar = create_build_context_tar(context_dir)?;

    let mut builder = BuildImageOptionsBuilder::default()
        .dockerfile(dockerfile_str)
        .t(tag)
        .rm(true)
        .platform(&target_platform);

    // Pass build args to Docker.
    if !effective_build_args.is_empty() {
        builder = builder.buildargs(&effective_build_args);
    }

    let options = builder.build();

    let body = bollard::body_full(bytes::Bytes::from(context_tar));
    let mut stream = docker.build_image(options, None, Some(body));
    let no_progress_secs: u64 = std::env::var("OPENSHELL_BUILD_NO_PROGRESS_TIMEOUT_SECS")
        .ok()
        .and_then(|s| s.parse().ok())
        .filter(|&n| n > 0)
        .unwrap_or(DEFAULT_BUILD_NO_PROGRESS_TIMEOUT_SECS);
    let no_progress_timeout = Duration::from_secs(no_progress_secs);

    loop {
        let next = match timeout(no_progress_timeout, stream.next()).await {
            Ok(Some(result)) => result,
            Ok(None) => break,
            Err(_) => {
                return Err(miette::miette!(
                    "Docker build produced no output for {}s. This usually means the container \
                     runtime is under-provisioned (CPU/memory) and the builder has deadlocked; \
                     check `docker info` (NCPU, MemTotal) and increase Colima/Docker Desktop \
                     resources before retrying. If a legitimate build step is just quiet, raise \
                     the threshold with OPENSHELL_BUILD_NO_PROGRESS_TIMEOUT_SECS=<secs>.",
                    no_progress_timeout.as_secs()
                ));
            }
        };

        let info = next
            .into_diagnostic()
            .wrap_err("Docker build stream error")?;

        // Forward build output lines.
        if let Some(stream_line) = &info.stream {
            let trimmed = stream_line.trim_end();
            if !trimmed.is_empty() {
                on_log(trimmed.to_string());
            }
        }

        // Check for build errors.
        if let Some(error_detail) = &info.error_detail {
            let msg = error_detail
                .message
                .as_deref()
                .unwrap_or("unknown build error");
            return Err(miette::miette!("Docker build failed: {msg}"));
        }
    }

    Ok(())
}

/// Create a tar archive of a directory for use as a Docker build context.
///
/// Walks `context_dir` recursively, respects a `.dockerignore` file if present,
/// and adds matching files with paths relative to the context root.
fn create_build_context_tar(context_dir: &Path) -> Result<Vec<u8>> {
    let ignore_patterns = load_dockerignore(context_dir);

    let mut builder = tar::Builder::new(Vec::new());

    // Walk the directory tree and add entries, skipping ignored paths.
    walk_and_add(context_dir, context_dir, &ignore_patterns, &mut builder)?;

    builder
        .into_inner()
        .into_diagnostic()
        .wrap_err("failed to finalize build context tar")
}

/// Recursively walk a directory and add entries to a tar archive,
/// skipping paths that match `.dockerignore` patterns.
fn walk_and_add(
    root: &Path,
    current: &Path,
    ignore_patterns: &[IgnorePattern],
    builder: &mut tar::Builder<Vec<u8>>,
) -> Result<()> {
    let entries = std::fs::read_dir(current)
        .into_diagnostic()
        .wrap_err_with(|| format!("failed to read directory: {}", current.display()))?;

    for entry in entries {
        let entry = entry
            .into_diagnostic()
            .wrap_err("failed to read directory entry")?;
        let path = entry.path();
        let relative = path
            .strip_prefix(root)
            .unwrap_or(&path)
            .to_string_lossy()
            .to_string();

        // Normalize to forward slashes for pattern matching.
        let relative_normalized = relative.replace('\\', "/");

        if is_ignored(&relative_normalized, path.is_dir(), ignore_patterns) {
            continue;
        }

        if path.is_dir() {
            walk_and_add(root, &path, ignore_patterns, builder)?;
        } else {
            // Use append_path_with_name which handles GNU LongName extensions
            // for paths exceeding 100 bytes (the POSIX tar name field limit).
            builder
                .append_path_with_name(&path, &relative_normalized)
                .into_diagnostic()
                .wrap_err_with(|| format!("failed to add file to tar: {relative_normalized}"))?;
        }
    }

    Ok(())
}

/// A parsed `.dockerignore` pattern.
#[derive(Debug, Clone)]
struct IgnorePattern {
    /// The glob pattern (may contain `*`, `**`, `?`).
    pattern: String,
    /// Whether this is a negation pattern (starts with `!`).
    negated: bool,
}

/// Load and parse a `.dockerignore` file from the context directory.
///
/// Returns an empty list if no `.dockerignore` exists.
fn load_dockerignore(context_dir: &Path) -> Vec<IgnorePattern> {
    let dockerignore_path = context_dir.join(".dockerignore");
    let Ok(contents) = std::fs::read_to_string(&dockerignore_path) else {
        return Vec::new();
    };

    contents
        .lines()
        .map(str::trim)
        .filter(|line| !line.is_empty() && !line.starts_with('#'))
        .map(|line| {
            line.strip_prefix('!').map_or_else(
                || IgnorePattern {
                    pattern: line.to_string(),
                    negated: false,
                },
                |rest| IgnorePattern {
                    pattern: rest.trim().to_string(),
                    negated: true,
                },
            )
        })
        .collect()
}

/// Check whether a relative path should be ignored based on `.dockerignore` patterns.
///
/// Uses a simple glob-matching approach: patterns are matched against the
/// full relative path. A leading `/` anchors to the context root. The last
/// matching pattern wins (negation patterns re-include files).
fn is_ignored(relative_path: &str, is_dir: bool, patterns: &[IgnorePattern]) -> bool {
    let mut ignored = false;

    for pat in patterns {
        let pattern = pat.pattern.trim_start_matches('/');

        // Check if the pattern matches.
        let matches = glob_match(pattern, relative_path, is_dir);

        if matches {
            ignored = !pat.negated;
        }
    }

    ignored
}

/// Simple glob matching supporting `*`, `**`, and `?`.
///
/// This is intentionally simple — it covers the common `.dockerignore` cases
/// without pulling in a full glob crate. For complex patterns, Docker's own
/// builder handles them during the build step anyway; this is just for
/// reducing the context tar size.
fn glob_match(pattern: &str, path: &str, is_dir: bool) -> bool {
    // Handle ** prefix (match any number of directories)
    if let Some(rest) = pattern.strip_prefix("**/") {
        // Match against the path itself and any suffix after a /
        if glob_match(rest, path, is_dir) {
            return true;
        }
        for (idx, _) in path.match_indices('/') {
            if glob_match(rest, &path[idx + 1..], is_dir) {
                return true;
            }
        }
        return false;
    }

    // Handle pattern that is just a name (no slashes) — match against any
    // path component or as a prefix directory match.
    if !pattern.contains('/') {
        // Match the final component of the path.
        let basename = path.rsplit('/').next().unwrap_or(path);
        if simple_glob_match(pattern, basename) {
            return true;
        }
        // Also match as a directory prefix: pattern "node_modules" should
        // match "node_modules/foo/bar".
        if let Some(first) = path.split('/').next()
            && simple_glob_match(pattern, first)
        {
            return true;
        }
        return false;
    }

    // Pattern contains slashes — match against the full path.
    simple_glob_match(pattern, path) || (is_dir && path.starts_with(pattern.trim_end_matches('/')))
}

/// Match a simple glob pattern (with `*` and `?` but not `**`) against a string.
fn simple_glob_match(pattern: &str, text: &str) -> bool {
    let mut p_star: Option<usize> = None;
    let mut t_star: Option<usize> = None;

    let p_bytes: Vec<char> = pattern.chars().collect();
    let t_bytes: Vec<char> = text.chars().collect();
    let mut pi = 0;
    let mut ti = 0;

    while ti < t_bytes.len() {
        if pi < p_bytes.len() && (p_bytes[pi] == '?' || p_bytes[pi] == t_bytes[ti]) {
            pi += 1;
            ti += 1;
        } else if pi < p_bytes.len() && p_bytes[pi] == '*' {
            p_star = Some(pi);
            t_star = Some(ti);
            pi += 1;
        } else if let Some(ps) = p_star {
            pi = ps + 1;
            t_star = Some(t_star.unwrap() + 1);
            ti = t_star.unwrap();
        } else {
            return false;
        }
    }

    while pi < p_bytes.len() && p_bytes[pi] == '*' {
        pi += 1;
    }

    pi == p_bytes.len()
}

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

    #[test]
    fn test_create_build_context_tar() {
        let dir = tempfile::tempdir().unwrap();
        let dir_path = dir.path();

        // Create a simple Dockerfile and a file.
        fs::write(dir_path.join("Dockerfile"), "FROM ubuntu:24.04\n").unwrap();
        fs::write(dir_path.join("hello.txt"), "hello world\n").unwrap();
        fs::create_dir(dir_path.join("subdir")).unwrap();
        fs::write(dir_path.join("subdir/nested.txt"), "nested\n").unwrap();

        let tar_bytes = create_build_context_tar(dir_path).unwrap();
        assert!(!tar_bytes.is_empty());

        // Verify the tar contains the expected entries.
        let mut archive = tar::Archive::new(tar_bytes.as_slice());
        let entries: Vec<String> = archive
            .entries()
            .unwrap()
            .filter_map(std::result::Result::ok)
            .map(|e| e.path().unwrap().to_string_lossy().to_string())
            .collect();

        assert!(entries.iter().any(|e| e.contains("Dockerfile")));
        assert!(entries.iter().any(|e| e.contains("hello.txt")));
        assert!(entries.iter().any(|e| e.contains("subdir/nested.txt")));
    }

    #[test]
    fn test_dockerignore_excludes_files() {
        let dir = tempfile::tempdir().unwrap();
        let dir_path = dir.path();

        fs::write(dir_path.join("Dockerfile"), "FROM ubuntu:24.04\n").unwrap();
        fs::write(dir_path.join("hello.txt"), "hello\n").unwrap();
        fs::write(dir_path.join("secret.env"), "SECRET=foo\n").unwrap();
        fs::create_dir(dir_path.join("node_modules")).unwrap();
        fs::write(dir_path.join("node_modules/pkg.js"), "module\n").unwrap();
        fs::write(dir_path.join(".dockerignore"), "*.env\nnode_modules\n").unwrap();

        let tar_bytes = create_build_context_tar(dir_path).unwrap();
        let mut archive = tar::Archive::new(tar_bytes.as_slice());
        let entries: Vec<String> = archive
            .entries()
            .unwrap()
            .filter_map(std::result::Result::ok)
            .map(|e| e.path().unwrap().to_string_lossy().to_string())
            .collect();

        assert!(entries.iter().any(|e| e.contains("Dockerfile")));
        assert!(entries.iter().any(|e| e.contains("hello.txt")));
        assert!(!entries.iter().any(|e| e.contains("secret.env")));
        assert!(!entries.iter().any(|e| e.contains("node_modules")));
    }

    #[test]
    fn test_dockerignore_negation() {
        let dir = tempfile::tempdir().unwrap();
        let dir_path = dir.path();

        fs::write(dir_path.join("Dockerfile"), "FROM ubuntu:24.04\n").unwrap();
        fs::write(dir_path.join("a.log"), "log\n").unwrap();
        fs::write(dir_path.join("important.log"), "keep\n").unwrap();
        fs::write(dir_path.join(".dockerignore"), "*.log\n!important.log\n").unwrap();

        let tar_bytes = create_build_context_tar(dir_path).unwrap();
        let mut archive = tar::Archive::new(tar_bytes.as_slice());
        let entries: Vec<String> = archive
            .entries()
            .unwrap()
            .filter_map(std::result::Result::ok)
            .map(|e| e.path().unwrap().to_string_lossy().to_string())
            .collect();

        assert!(!entries.iter().any(|e| e.contains("a.log")));
        assert!(entries.iter().any(|e| e.contains("important.log")));
    }

    #[test]
    fn test_long_path_exceeding_100_bytes() {
        let dir = tempfile::tempdir().unwrap();
        let dir_path = dir.path();

        // Build a nested path that exceeds 100 bytes when relative to root.
        let deep_dir = dir_path.join(
            "a/deeply/nested/directory/path/that/exceeds/one/hundred/bytes/total/from/the/build/context/root",
        );
        fs::create_dir_all(&deep_dir).unwrap();
        fs::write(deep_dir.join("file.txt"), "deep content\n").unwrap();
        fs::write(dir_path.join("Dockerfile"), "FROM ubuntu:24.04\n").unwrap();

        let tar_bytes = create_build_context_tar(dir_path).unwrap();
        let mut archive = tar::Archive::new(tar_bytes.as_slice());
        let entries: Vec<String> = archive
            .entries()
            .unwrap()
            .filter_map(std::result::Result::ok)
            .map(|e| e.path().unwrap().to_string_lossy().to_string())
            .collect();

        let long_entry = entries.iter().find(|e| e.contains("file.txt"));
        assert!(
            long_entry.is_some(),
            "tar should contain deeply nested file; entries: {entries:?}"
        );
        assert!(
            long_entry.unwrap().len() > 100,
            "path should exceed 100 bytes to exercise GNU LongName handling"
        );
    }

    #[test]
    fn test_simple_glob_match() {
        assert!(simple_glob_match("*.txt", "hello.txt"));
        assert!(!simple_glob_match("*.txt", "hello.rs"));
        assert!(simple_glob_match("test?", "test1"));
        assert!(!simple_glob_match("test?", "test12"));
        assert!(simple_glob_match("*", "anything"));
        assert!(simple_glob_match("foo*bar", "fooXYZbar"));
    }

    #[test]
    fn test_glob_match_double_star() {
        assert!(glob_match("**/*.log", "a/b/c.log", false));
        assert!(glob_match("**/*.log", "c.log", false));
        assert!(!glob_match("**/*.log", "c.txt", false));
    }

    #[test]
    fn test_is_ignored_directory_prefix() {
        let patterns = vec![IgnorePattern {
            pattern: "node_modules".to_string(),
            negated: false,
        }];
        assert!(is_ignored("node_modules", true, &patterns));
        assert!(is_ignored("node_modules/foo.js", false, &patterns));
    }

    #[test]
    fn test_normalize_docker_platform_maps_docker_desktop_arch() {
        assert_eq!(
            normalize_docker_platform("linux", "aarch64").unwrap(),
            "linux/arm64"
        );
        assert_eq!(
            normalize_docker_platform("linux", "x86_64").unwrap(),
            "linux/amd64"
        );
    }

    #[test]
    fn test_normalize_docker_platform_case_insensitive_arch() {
        // Some remote or non-standard Docker daemons return mixed-case arch strings.
        assert_eq!(
            normalize_docker_platform("linux", "ARM64").unwrap(),
            "linux/arm64"
        );
        assert_eq!(
            normalize_docker_platform("linux", "X86_64").unwrap(),
            "linux/amd64"
        );
    }

    #[test]
    fn test_insert_implicit_platform_build_args_native() {
        // Native builds use one platform for both target and build args.
        let mut build_args = HashMap::new();
        insert_implicit_platform_build_args(&mut build_args, "linux/arm/v7", "linux/arm/v7")
            .unwrap();

        assert_eq!(build_args.get("TARGETPLATFORM").unwrap(), "linux/arm/v7");
        assert_eq!(build_args.get("TARGETOS").unwrap(), "linux");
        assert_eq!(build_args.get("TARGETARCH").unwrap(), "arm");
        assert_eq!(build_args.get("TARGETVARIANT").unwrap(), "v7");
        assert_eq!(build_args.get("BUILDPLATFORM").unwrap(), "linux/arm/v7");
        assert_eq!(build_args.get("BUILDOS").unwrap(), "linux");
        assert_eq!(build_args.get("BUILDARCH").unwrap(), "arm");
        assert_eq!(build_args.get("BUILDVARIANT").unwrap(), "v7");
    }

    #[test]
    fn test_insert_implicit_platform_build_args_cross_compile() {
        // Cross-builds keep daemon BUILD* args separate from target args.
        let mut build_args = HashMap::new();
        insert_implicit_platform_build_args(&mut build_args, "linux/arm64", "linux/amd64").unwrap();

        assert_eq!(build_args.get("TARGETPLATFORM").unwrap(), "linux/arm64");
        assert_eq!(build_args.get("TARGETARCH").unwrap(), "arm64");
        assert_eq!(build_args.get("BUILDPLATFORM").unwrap(), "linux/amd64");
        assert_eq!(build_args.get("BUILDARCH").unwrap(), "amd64");
        // Leaving variant args absent preserves Dockerfile ARG defaults.
        assert!(!build_args.contains_key("TARGETVARIANT"));
        assert!(!build_args.contains_key("BUILDVARIANT"));
    }

    #[test]
    fn test_insert_implicit_platform_build_args_trailing_slash_rejected() {
        let mut build_args = HashMap::new();
        let result =
            insert_implicit_platform_build_args(&mut build_args, "linux/arm64/", "linux/amd64");
        assert!(
            result.is_err(),
            "trailing slash should be rejected as a malformed variant segment"
        );
    }
}