//! Shell helper commands exposed to package build/post-install scripts.

use crate::builder::{EnvVars, set_env_var};
use anyhow::{Context, Result};
use std::fs;
use std::path::{Path, PathBuf};
use tempfile::TempDir;

/// Internal staging namespace reserved inside `DESTDIR`.
pub const INTERNAL_DEPOT_DIR: &str = ".depot";
/// Internal split-output staging root inside `DESTDIR`.
pub const INTERNAL_OUTPUTS_DIR: &str = ".depot/outputs";

/// Ephemeral helper command directory to prepend to PATH while running scripts.
pub struct ShellHelpers {
    _tempdir: TempDir,
    path_value: String,
    outputs_dir: PathBuf,
}

impl ShellHelpers {
    /// Create helper commands for a given staging tree (`DESTDIR`).
    pub fn new(destdir: &Path) -> Result<Self> {
        let tempdir = tempfile::tempdir().context("Failed to create shell helper tempdir")?;
        let bin_dir = tempdir.path().join("bin");
        fs::create_dir_all(&bin_dir)
            .with_context(|| format!("Failed to create helper bin dir: {}", bin_dir.display()))?;

        let haul_path = bin_dir.join("haul");
        fs::write(&haul_path, HAUL_SCRIPT).with_context(|| {
            format!(
                "Failed to write shell helper command: {}",
                haul_path.display()
            )
        })?;
        #[cfg(unix)]
        {
            use std::os::unix::fs::PermissionsExt;
            let mut perms = fs::metadata(&haul_path)
                .with_context(|| format!("Failed to stat helper: {}", haul_path.display()))?
                .permissions();
            perms.set_mode(0o755);
            fs::set_permissions(&haul_path, perms)
                .with_context(|| format!("Failed to chmod helper: {}", haul_path.display()))?;
        }

        let subdestdir_path = bin_dir.join("subdestdir");
        fs::write(&subdestdir_path, SUBDESTDIR_SCRIPT).with_context(|| {
            format!(
                "Failed to write shell helper command: {}",
                subdestdir_path.display()
            )
        })?;
        #[cfg(unix)]
        {
            use std::os::unix::fs::PermissionsExt;
            let mut perms = fs::metadata(&subdestdir_path)
                .with_context(|| format!("Failed to stat helper: {}", subdestdir_path.display()))?
                .permissions();
            perms.set_mode(0o755);
            fs::set_permissions(&subdestdir_path, perms).with_context(|| {
                format!("Failed to chmod helper: {}", subdestdir_path.display())
            })?;
        }

        let parent_path = std::env::var("PATH").unwrap_or_default();
        let helper_path = bin_dir.to_string_lossy().into_owned();
        let path_value = if parent_path.is_empty() {
            helper_path
        } else {
            format!("{}:{}", helper_path, parent_path)
        };

        Ok(Self {
            _tempdir: tempdir,
            path_value,
            outputs_dir: destdir.join(INTERNAL_OUTPUTS_DIR),
        })
    }

    /// Apply helper-related variables to an environment vector used with `prepare_command`.
    pub fn apply_to_env_vars(&self, env_vars: &mut EnvVars) {
        set_env_var(env_vars, "PATH", self.path_value.clone());
        set_env_var(
            env_vars,
            "DEPOT_OUTPUTS_DIR",
            self.outputs_dir.to_string_lossy().into_owned(),
        );
        set_env_var(env_vars, "DEPOT_INTERNAL_DIR", INTERNAL_DEPOT_DIR);
    }

    /// Apply helper-related variables directly to a `std::process::Command`.
    pub fn apply_to_command(&self, cmd: &mut std::process::Command) {
        cmd.env("PATH", &self.path_value)
            .env("DEPOT_OUTPUTS_DIR", &self.outputs_dir)
            .env("DEPOT_INTERNAL_DIR", INTERNAL_DEPOT_DIR);
    }
}

/// Convert a package name into a safe shell identifier suffix.
pub fn shell_ident_suffix(pkg_name: &str) -> String {
    let mut out = String::with_capacity(pkg_name.len().max(1));
    for ch in pkg_name.chars() {
        if ch.is_ascii_alphanumeric() {
            out.push(ch.to_ascii_uppercase());
        } else {
            out.push('_');
        }
    }
    if out.is_empty() {
        out.push('_');
    }
    if out.as_bytes().first().is_some_and(|b| b.is_ascii_digit()) {
        out.insert(0, '_');
    }
    out
}

const HAUL_SCRIPT: &str = r#"#!/bin/sh
set -eu

usage() {
    echo "Usage: haul <output-package> <path-pattern> [path-pattern ...]" >&2
    exit 2
}

fail() {
    echo "haul: $*" >&2
    exit 1
}

[ "$#" -ge 2 ] || usage

out_pkg=$1
shift

case "$out_pkg" in
    ""|.|..|*/*) fail "invalid output package name: $out_pkg" ;;
esac

[ "${DESTDIR:-}" != "" ] || fail "DESTDIR is not set"
[ "${DEPOT_OUTPUTS_DIR:-}" != "" ] || fail "DEPOT_OUTPUTS_DIR is not set"

src_root=$DESTDIR
out_root=$DEPOT_OUTPUTS_DIR/$out_pkg

case "$src_root" in
    */) src_root=${src_root%/} ;;
esac
case "$out_root" in
    */) out_root=${out_root%/} ;;
esac

mkdir -p "$out_root"

tmp_matches=$(mktemp "${TMPDIR:-/tmp}/depot-haul.XXXXXX")
trap 'rm -f "$tmp_matches"' EXIT HUP INT TERM
: > "$tmp_matches"

collect_matches_for_pattern() {
    pattern=$1
    before_count=$(wc -l < "$tmp_matches" | tr -d '[:space:]')
    case "$pattern" in
        ""|/|/*|../*|*/../*|..)
            fail "unsafe pattern: $pattern"
            ;;
        .depot|.depot/*)
            fail "refusing to haul internal staging paths: $pattern"
            ;;
    esac

    if [ ! -d "$src_root" ]; then
        fail "DESTDIR does not exist: $src_root"
    fi

    find "$src_root" -mindepth 1 \
        ! -path "$DEPOT_OUTPUTS_DIR" ! -path "$DEPOT_OUTPUTS_DIR/*" \
        -print | LC_ALL=C sort |
    while IFS= read -r abs_path; do
        rel_path=${abs_path#"$src_root"/}
        [ "$rel_path" != "$abs_path" ] || continue
        case "$rel_path" in
            $pattern)
                printf '%s\n' "$rel_path" >> "$tmp_matches"
                ;;
        esac
    done

    after_count=$(wc -l < "$tmp_matches" | tr -d '[:space:]')
    if [ "$before_count" = "$after_count" ]; then
        fail "no matches for pattern: $pattern"
    fi
}

for pattern in "$@"; do
    collect_matches_for_pattern "$pattern"
done

LC_ALL=C sort -u "$tmp_matches" | while IFS= read -r rel_path; do
    [ -n "$rel_path" ] || continue
    src_path=$src_root/$rel_path

    if [ ! -e "$src_path" ] && [ ! -L "$src_path" ]; then
        # Path may already have been moved because an ancestor directory matched.
        continue
    fi

    dst_path=$out_root/$rel_path
    dst_parent=$(dirname "$dst_path")
    mkdir -p "$dst_parent"

    if [ -e "$dst_path" ] || [ -L "$dst_path" ]; then
        fail "destination already exists: $dst_path"
    fi

    mv "$src_path" "$dst_path"
done

# Clean empty directories left behind in the primary staging tree, but never
# touch the internal depot namespace.
find "$src_root" -depth -type d \
    ! -path "$src_root" \
    ! -path "$src_root/.depot" ! -path "$src_root/.depot/*" \
    -empty -exec rmdir {} + 2>/dev/null || true
"#;

const SUBDESTDIR_SCRIPT: &str = r#"#!/bin/sh
set -eu

fail() {
    echo "subdestdir: $*" >&2
    exit 1
}

[ "$#" -eq 1 ] || fail "usage: subdestdir <output-package>"
[ "${DEPOT_OUTPUTS_DIR:-}" != "" ] || fail "DEPOT_OUTPUTS_DIR is not set"

pkg=$1
case "$pkg" in
    ""|.|..|*/*) fail "invalid output package name: $pkg" ;;
esac

path=$DEPOT_OUTPUTS_DIR/$pkg
mkdir -p "$path"
printf '%s\n' "$path"
"#;

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

    #[test]
    fn shell_ident_suffix_normalizes_package_names() {
        assert_eq!(shell_ident_suffix("clang"), "CLANG");
        assert_eq!(shell_ident_suffix("llvm-libgcc"), "LLVM_LIBGCC");
        assert_eq!(shell_ident_suffix("3foo"), "_3FOO");
        assert_eq!(shell_ident_suffix("foo.bar+baz"), "FOO_BAR_BAZ");
    }
}