#!/bin/sh
# Installs amp, Amp's command-line interface:
#
#   curl -fsSL https://dl.amp.motor.dev | sh
#
# It installs the latest release into $AMP_INSTALL_DIR (default: ~/.local/bin). Set AMP_VERSION to
# install a specific release. If the directory isn't on the PATH, the script adds it in the profile of
# your shell (zsh, bash, fish, or ~/.profile for other shells). Set AMP_NO_MODIFY_PATH=1 to get
# instructions instead.

set -e -u

BASE="${AMP_DIST_URL:-https://dl.amp.motor.dev}"
DIR="${AMP_INSTALL_DIR:-$HOME/.local/bin}"

fail() {
    echo "install.sh: $1" >&2
    exit 1
}

case "$(uname -s)" in
    Darwin) OS=darwin ;;
    Linux) OS=linux ;;
    *) fail "amp isn't available for $(uname -s)" ;;
esac
case "$(uname -m)" in
    arm64 | aarch64) ARCH=arm64 ;;
    x86_64 | amd64) ARCH=amd64 ;;
    *) fail "amp isn't available for $(uname -m)" ;;
esac
# A shell under Rosetta reports x86_64 on an Apple silicon Mac: prefer the native binary.
if [ "$OS" = darwin ] && [ "$ARCH" = amd64 ] && [ "$(sysctl -n hw.optional.arm64 2>/dev/null)" = 1 ]; then
    ARCH=arm64
fi
TARGET="$OS-$ARCH"

download() {
    if command -v curl >/dev/null 2>&1; then
        curl -fsSL -o "$2" "$1" || fail "can't download $1"
    elif command -v wget >/dev/null 2>&1; then
        wget -q -O "$2" "$1" || fail "can't download $1"
    else
        fail "install curl or wget, then try again"
    fi
}

checksum() {
    if command -v sha256sum >/dev/null 2>&1; then
        sha256sum "$1" | cut -d' ' -f1
    else
        shasum -a 256 "$1" | cut -d' ' -f1
    fi
}

WORK="$(mktemp -d)"
trap 'rm -rf "$WORK"' EXIT

VERSION="${AMP_VERSION:-}"
if [ -z "$VERSION" ]; then
    download "$BASE/index.json" "$WORK/index.json"
    VERSION="$(tr -d ' \n' < "$WORK/index.json" | sed -n 's/.*"latest":"\([0-9_]*\)".*/\1/p')"
    [ -n "$VERSION" ] || fail "the published index doesn't name a latest version"
fi

download "$BASE/releases/$VERSION/manifest.json" "$WORK/manifest.json"
EXPECTED="$(tr -d ' \n' < "$WORK/manifest.json" | sed -n "s/.*\"$TARGET\":{\"sha256\":\"\([0-9a-f]*\)\".*/\1/p")"
[ -n "$EXPECTED" ] || fail "amp $VERSION isn't published for $TARGET"

echo "Downloading amp $VERSION for $TARGET"
download "$BASE/releases/$VERSION/amp-$TARGET.gz" "$WORK/amp.gz"
[ "$(checksum "$WORK/amp.gz")" = "$EXPECTED" ] || fail "the download doesn't match its checksum; try again"
gunzip "$WORK/amp.gz"
chmod +x "$WORK/amp"

mkdir -p "$DIR"
mv -f "$WORK/amp" "$DIR/amp"
echo "Installed amp $VERSION to $DIR/amp"

# Write the directory with $HOME, so that the profile line is easy to read.
case "$DIR" in
    "$HOME"/*) SHOWN="\$HOME/${DIR#"$HOME"/}" ;;
    *) SHOWN="$DIR" ;;
esac
LINE="export PATH=\"$SHOWN:\$PATH\""
case "$(basename "${SHELL:-sh}")" in
    zsh) PROFILE="${ZDOTDIR:-$HOME}/.zshrc" ;;
    bash)
        # macOS opens login shells, which read ~/.bash_profile; Linux opens shells that read ~/.bashrc.
        if [ "$OS" = darwin ]; then PROFILE="$HOME/.bash_profile"; else PROFILE="$HOME/.bashrc"; fi
        ;;
    fish)
        PROFILE="${XDG_CONFIG_HOME:-$HOME/.config}/fish/conf.d/amp.fish"
        LINE="fish_add_path \"$SHOWN\""
        ;;
    *) PROFILE="$HOME/.profile" ;;
esac

case ":${PATH}:" in
    *:"$DIR":*)
        # Another amp earlier on the PATH would hide this one.
        FOUND="$(command -v amp 2>/dev/null || true)"
        if [ -n "$FOUND" ] && [ "$FOUND" != "$DIR/amp" ]; then
            echo
            echo "warning: $FOUND comes before $DIR/amp on your PATH; remove it, or put $DIR first"
        fi
        ;;
    *)
        if [ -n "${AMP_NO_MODIFY_PATH:-}" ]; then
            echo
            echo "$DIR isn't on your PATH. Add this line to $PROFILE:"
            echo "    $LINE"
        elif grep -qsF "$LINE" "$PROFILE"; then
            echo
            echo "$PROFILE adds $DIR to your PATH. Open a new shell to use amp."
        elif mkdir -p "$(dirname "$PROFILE")" && printf '\n# Added by the amp installer\n%s\n' "$LINE" >> "$PROFILE"; then
            echo
            echo "Added $DIR to your PATH in $PROFILE. Open a new shell, or run this line to use amp now:"
            echo "    $LINE"
        else
            echo
            echo "Can't write $PROFILE. Add this line to the profile of your shell:"
            echo "    $LINE"
        fi
        ;;
esac

echo
echo "Run \`amp learn\` to learn how to use amp. Run \`amp update\` to get new releases."