#!/bin/sh
# Preflight: check that this machine has what the stack needs, record where each
# tool lives, and set up tools/.venv - before any `wikitool` command can run.
#
#   tools/preflight.sh                      check, record, set up
#   tools/preflight.sh --set rg=/opt/rg/rg  use a path the user named
#
# As the release asset `preflight.sh` - a copy with no tools/prerequisites.txt next
# to it - the script is the first install step instead: it downloads the stack
# release named in RELEASE_ARCHIVE_URL / RELEASE_CHECKSUM_URL, checks the sha256,
# unpacks it into <script folder>/chemenu (or --into <path>), and runs the copy of
# this script inside the unpacked tree, which does everything above.
#
#   preflight.sh [--into <path>] [--archive <tarball>] [--set <tool>=<path>]...
#
# --archive uses a local tarball instead of a download; <tarball>.sha256 has to lie
# next to it. Release builds fill the two URL lines below; a tree copy leaves them empty.
#
# Exit 0: everything is in place and .wikitool-tools.json is complete.
# Exit 42: the user has to act. The output says what, why, the command that fixes
#          it and what happens next; show it verbatim and wait (AGENTS.md § Tool
#          error contract). Never install anything on the user's behalf.
# Exit 1: this script was called wrongly, a download or unpack failed (nothing is
#         unpacked then), or the tree next to it is incomplete.
#
# POSIX sh on purpose: it has to run before Python is known to exist, under dash,
# bash and the Git Bash that Claude Code uses on Windows. The PowerShell
# counterpart is tools/preflight.ps1; what both check is tools/prerequisites.txt.
# The procedure around this script: instructions/preflight.md.
#
# Two variables exist for the test suite and are read nowhere else:
# CHEMENU_PREFLIGHT_PLATFORM (windows|macos|linux) and
# CHEMENU_PREFLIGHT_LONGPATHS (0|1) stand in for `uname` and the registry.

set -u

DIR=$(CDPATH='' cd -- "$(dirname -- "$0")" && pwd -P)
ROOT=$(dirname -- "$DIR")
MANIFEST="$DIR/prerequisites.txt"
TOOLS_FILE="$ROOT/.wikitool-tools.json"
VENV="$DIR/.venv"
REQUIREMENTS="$DIR/requirements.txt"
STAMP="$VENV/.chemenu-requirements.sha256"
SELF="tools/preflight.sh"

# Filled in by the release build, in the copy attached to the release; empty in a tree.
RELEASE_ARCHIVE_URL=''
RELEASE_CHECKSUM_URL=''

PYPROBE='import sys; print("%d.%d" % sys.version_info[:2]); print(sys.executable)'

usage() {
    cat <<'EOF'
usage: tools/preflight.sh [--set <tool>=<path>]...
       preflight.sh [--into <path>] [--archive <tarball>] [--set <tool>=<path>]...

Checks the tools this stack needs (tools/prerequisites.txt), records their paths
in .wikitool-tools.json and sets up tools/.venv. Exit 0 means ready; exit 42
means the user has to act - the output says how.

The second form is the release asset: it downloads the release (or takes
--archive), checks its sha256, unpacks it into <script folder>/chemenu or --into,
and runs the preflight inside it.
EOF
}

# --- arguments ----------------------------------------------------------------

SETS=""
INTO="" ARCHIVE=""
while [ $# -gt 0 ]; do
    case "$1" in
        --into|--archive)
            if [ $# -lt 2 ] || [ -z "$2" ]; then
                echo "preflight: $1 needs a path" >&2
                exit 1
            fi
            if [ "$1" = --into ]; then INTO=$2; else ARCHIVE=$2; fi
            shift
            ;;
        --set)
            if [ $# -lt 2 ]; then
                echo "preflight: --set needs <tool>=<path>" >&2
                exit 1
            fi
            SETS="$SETS
$2"
            shift
            ;;
        --set=*) SETS="$SETS
${1#--set=}" ;;
        -h|--help) usage; exit 0 ;;
        *) echo "preflight: unknown argument: $1" >&2; usage >&2; exit 1 ;;
    esac
    shift
done

ASSET=0
if [ ! -f "$MANIFEST" ]; then
    ASSET=1
elif [ -n "$INTO$ARCHIVE" ]; then
    echo "preflight: --into and --archive belong to the release asset; inside a stack tree there is nothing to unpack." >&2
    exit 1
fi

# --- platform -----------------------------------------------------------------

if [ -n "${CHEMENU_PREFLIGHT_PLATFORM:-}" ]; then
    PLATFORM=$CHEMENU_PREFLIGHT_PLATFORM
else
    case "$(uname -s 2>/dev/null)" in
        MINGW*|MSYS*|CYGWIN*) PLATFORM=windows ;;
        Darwin) PLATFORM=macos ;;
        *) PLATFORM=linux ;;
    esac
fi

# A path as the rest of the machine spells it: under Git Bash `/c/Tools/rg.exe`
# becomes `C:\Tools\rg.exe`, which is what Python and PowerShell read back.
native_path() {
    if [ "$PLATFORM" = windows ] && command -v cygpath >/dev/null 2>&1; then
        cygpath -w "$1"
    else
        printf '%s\n' "$1"
    fi
}

# --- problems and the guidance block --------------------------------------------

PROBLEMS=0
GUIDE=""
BAD_SET=0

# problem <what> <why> <fix, may span lines>
problem() {
    PROBLEMS=$((PROBLEMS + 1))
    fix=$(printf '%s\n' "$3" | sed '2,$s/^/         /')
    GUIDE="$GUIDE
$PROBLEMS) $1
   Why:  $2
   Fix:  $fix
   Next: Tell the agent once this is done - it runs this check again.
"
}

stop() {
    if [ "$PROBLEMS" -eq 1 ]; then
        noun="1 thing needs"
    else
        noun="$PROBLEMS things need"
    fi
    echo ""
    echo "STOP - $noun your attention before this wiki can run."
    echo "(Agent: show this output to the user exactly as it is, then wait. Do not install"
    echo "anything yourself and do not work around it.)"
    printf '%s' "$GUIDE"
    exit 42
}

longpaths_enabled() {
    if [ -n "${CHEMENU_PREFLIGHT_LONGPATHS:-}" ]; then
        [ "$CHEMENU_PREFLIGHT_LONGPATHS" = 1 ]
        return
    fi
    # MSYS would rewrite the `/v` into a path without the exclusion. An unreadable
    # key counts as "off": the limit then protects a machine it did not have to.
    answer=$(MSYS2_ARG_CONV_EXCL='*' reg query 'HKLM\SYSTEM\CurrentControlSet\Control\FileSystem' \
        /v LongPathsEnabled 2>/dev/null) || return 1
    case "$answer" in *0x1*) return 0 ;; esac
    return 1
}

# Length in UTF-16 code units, which is what MAX_PATH counts.
utf16_length() {
    if command -v iconv >/dev/null 2>&1; then
        bytes=$(printf '%s' "$1" | iconv -f UTF-8 -t UTF-16LE 2>/dev/null | wc -c | tr -d ' ')
        if [ "${bytes:-0}" -gt 0 ]; then
            echo $((bytes / 2))
            return
        fi
    fi
    echo ${#1}
}

# --- asset mode: the release asset unpacks the stack, then hands over ------------------
#
# Only when no tools/prerequisites.txt lies next to this script. Nothing here reads
# the tree; the folder limit comes out of the archive itself. The tools the tree copy
# checks (Python, git, rg) are not needed until that copy runs.

WORK=""
cleanup() {
    [ -z "$WORK" ] || rm -rf "$WORK"
    [ -z "${UNPACK:-}" ] || rm -rf "$UNPACK"
}

asset_fail() { # <message>
    echo "preflight: $1" >&2
    exit 1
}

sha256_of() { # <file>
    if command -v sha256sum >/dev/null 2>&1; then
        sha256sum "$1" | cut -d' ' -f1
    else
        shasum -a 256 "$1" | cut -d' ' -f1
    fi
}

asset_mode() {
    # GNU tar reads `C:` as a host name; Git Bash has to hand it `/c/...`.
    if [ "$PLATFORM" = windows ] && command -v cygpath >/dev/null 2>&1; then
        [ -z "$ARCHIVE" ] || ARCHIVE=$(cygpath -u "$ARCHIVE")
        [ -z "$INTO" ] || INTO=$(cygpath -u "$INTO")
    fi
    if [ -n "$INTO" ]; then
        case "$INTO" in /*) TARGET=$INTO ;; *) TARGET="$(pwd)/$INTO" ;; esac
    else
        TARGET="$DIR/chemenu"
    fi
    TARGET=${TARGET%/}
    if [ -e "$TARGET" ] || [ -L "$TARGET" ]; then
        asset_fail "$(native_path "$TARGET") already exists - nothing was unpacked. Choose another folder with --into <path>, or move the existing one away."
    fi

    if [ -z "$ARCHIVE" ] && { [ -z "$RELEASE_ARCHIVE_URL" ] || [ -z "$RELEASE_CHECKSUM_URL" ]; }; then
        asset_fail "this copy of the script does not come from a release (it has no download address). Download preflight.sh from the release page, or pass --archive <tarball>."
    fi
    if [ -n "$ARCHIVE" ]; then
        [ -f "$ARCHIVE" ] || asset_fail "--archive: $ARCHIVE is not a file."
        [ -f "$ARCHIVE.sha256" ] || asset_fail "--archive: $ARCHIVE.sha256 is missing - the checksum file has to lie next to the tarball."
    fi

    # What has to be here for the download, tested before anything is fetched.
    missing=""
    if [ -z "$ARCHIVE" ] && ! command -v curl >/dev/null 2>&1; then missing="$missing curl"; fi
    command -v tar >/dev/null 2>&1 || missing="$missing tar"
    command -v sha256sum >/dev/null 2>&1 || command -v shasum >/dev/null 2>&1 || missing="$missing sha256sum"
    if [ -n "$missing" ]; then
        case "$PLATFORM" in
            macos) hint="brew install$missing" ;;
            windows) hint="Git for Windows (https://gitforwindows.org) provides all of them in Git Bash." ;;
            *) hint="sudo apt install$(printf '%s' "$missing" | sed 's/ sha256sum/ coreutils/')" ;;
        esac
        problem "Tools needed to fetch and unpack the stack could not be found:$missing" \
            "the first step downloads the release, checks its checksum and unpacks it" \
            "$hint"
        stop
    fi

    trap cleanup EXIT
    WORK=$(mktemp -d "${TMPDIR:-/tmp}/chemenu-preflight.XXXXXX") || asset_fail "could not create a temporary folder."
    if [ -n "$ARCHIVE" ]; then
        archive=$ARCHIVE
        checksum=$ARCHIVE.sha256
    else
        archive="$WORK/${RELEASE_ARCHIVE_URL##*/}"
        checksum="$WORK/${RELEASE_CHECKSUM_URL##*/}"
        echo "Downloading $RELEASE_ARCHIVE_URL"
        curl -fsSL -o "$archive" "$RELEASE_ARCHIVE_URL" || asset_fail "the download failed: $RELEASE_ARCHIVE_URL (check the internet connection, then run this again)."
        curl -fsSL -o "$checksum" "$RELEASE_CHECKSUM_URL" || asset_fail "the download failed: $RELEASE_CHECKSUM_URL (check the internet connection, then run this again)."
    fi

    want=$(sed -n '1s/^\([0-9A-Fa-f]\{64\}\).*/\1/p' "$checksum" | tr 'A-F' 'a-f')
    [ -n "$want" ] || asset_fail "the checksum file holds no sha256 in its first line - nothing was unpacked."
    have=$(sha256_of "$archive" | tr 'A-F' 'a-f')
    if [ "$want" != "$have" ]; then
        asset_fail "the sha256 of the archive does not match its checksum file (expected $want, got $have) - nothing was unpacked. Delete the download and run this again."
    fi
    echo "sha256 OK"

    listing=$(tar -tzf "$archive" 2>/dev/null) || asset_fail "the archive could not be read - nothing was unpacked."
    tops=$(printf '%s\n' "$listing" | sed 's|^\./||; s|/.*||; /^\.\{0,1\}$/d')
    top=$(printf '%s\n' "$tops" | head -n 1)
    other=$(printf '%s\n' "$tops" | grep -v -x -F -- "$top" | head -n 1)
    if [ -z "$top" ] || [ -n "$other" ]; then
        asset_fail "the archive does not hold exactly one top-level folder - nothing was unpacked."
    fi

    manifest=$(tar -xOzf "$archive" "$top/tools/prerequisites.txt" 2>/dev/null) \
        || asset_fail "the archive holds no $top/tools/prerequisites.txt - nothing was unpacked."
    limit=$(printf '%s\n' "$manifest" | sed -n 's/^limit|install_dir_max|\([0-9][0-9]*\).*/\1/p' | head -n 1)

    if [ "$PLATFORM" = windows ] && [ -n "$limit" ] && ! longpaths_enabled; then
        folder=$(native_path "$TARGET")
        length=$(utf16_length "$folder")
        if [ "$length" -gt "$limit" ]; then
            problem "The folder this wiki would be installed in is too long ($length characters, at most $limit): $folder" \
                "Windows on this computer only allows paths of up to 259 characters, and the wiki's own files need the rest" \
                "Run this again with a shorter folder, for example: --into C:\\\\Chemenu
Alternatively, someone with administrator rights can turn on long paths in Windows."
            stop
        fi
    fi

    parent=$(dirname -- "$TARGET")
    mkdir -p "$parent" || asset_fail "could not create $parent."
    UNPACK="$parent/.chemenu-unpack.$$"
    mkdir "$UNPACK" || asset_fail "could not create a temporary folder next to the target."
    tar -xzf "$archive" -C "$UNPACK" || asset_fail "unpacking failed - the target was not created."
    [ -d "$UNPACK/$top" ] || asset_fail "unpacking produced no $top folder - the target was not created."
    mv "$UNPACK/$top" "$TARGET" || asset_fail "could not move the unpacked stack to $(native_path "$TARGET")."
    rm -rf "$UNPACK"
    UNPACK=""

    [ -f "$TARGET/tools/preflight.sh" ] || asset_fail "the unpacked stack has no tools/preflight.sh."
    echo "Unpacked into $(native_path "$TARGET")."
    echo "If a later step stops, run tools/preflight.sh from inside that folder."
    echo ""
    set --
    while IFS= read -r entry; do
        [ -n "$entry" ] || continue
        set -- "$@" --set "$entry"
    done <<EOT
$SETS
EOT
    trap - EXIT
    cleanup
    exec /bin/sh "$TARGET/tools/preflight.sh" "$@"
}

[ "$ASSET" -eq 0 ] || asset_mode

# --- the manifest ---------------------------------------------------------------

manifest_field() { # <kind> <name> <field number, 1-based>
    while IFS='|' read -r kind name rest; do
        case "$kind" in ''|'#'*) continue ;; esac
        if [ "$kind" = "$1" ] && [ "$name" = "$2" ]; then
            printf '%s|%s|%s\n' "$kind" "$name" "$rest" | cut -d'|' -f"$3"
            return 0
        fi
    done < "$MANIFEST"
    return 1
}

TOOLS=""
while IFS='|' read -r kind name minimum platforms rest; do
    case "$kind" in ''|'#'*) continue ;; esac
    [ "$kind" = tool ] || continue
    case "$name" in *[!a-z0-9]*|'') echo "preflight: bad tool name '$name' in $MANIFEST" >&2; exit 1 ;; esac
    if [ "$platforms" = all ] || [ "$platforms" = "$PLATFORM" ]; then
        TOOLS="$TOOLS $name"
    fi
done < "$MANIFEST"

# The install command for this machine's package manager, or every known one.
install_hint() { # <tool>
    choco=$(manifest_field tool "$1" 7)
    winget=$(manifest_field tool "$1" 8)
    brew=$(manifest_field tool "$1" 9)
    apt=$(manifest_field tool "$1" 10)
    pacman=$(manifest_field tool "$1" 11)
    hint=""
    case "$PLATFORM" in
        windows)
            if command -v choco >/dev/null 2>&1 && [ "$choco" != - ]; then
                hint="$choco   (in a terminal opened as administrator)"
            elif command -v winget >/dev/null 2>&1 && [ "$winget" != - ]; then
                hint=$winget
            fi ;;
        macos)
            if command -v brew >/dev/null 2>&1 && [ "$brew" != - ]; then hint=$brew; fi ;;
        *)
            if command -v apt-get >/dev/null 2>&1 && [ "$apt" != - ]; then
                hint=$apt
            elif command -v pacman >/dev/null 2>&1 && [ "$pacman" != - ]; then
                hint=$pacman
            fi ;;
    esac
    if [ -n "$hint" ]; then
        printf '%s\n' "$hint"
        return
    fi
    printf 'Install it with the package manager this computer uses, for example:\n'
    for entry in "choco:$choco" "winget:$winget" "brew:$brew" "apt:$apt" "pacman:$pacman"; do
        case "$entry" in *:-) continue ;; esac
        printf '  %s\n' "${entry#*:}"
    done
}

# --- version helpers ------------------------------------------------------------

# major.minor of the first version-looking token in $1 ("git version 2.47.1" -> 2.47)
version_of() {
    printf '%s\n' "$1" | sed -n '1{s/^[^0-9]*\([0-9][0-9]*\)\(\.[0-9][0-9]*\)\{0,1\}.*/\1\2/p;}'
}

version_ge() { # <have> <want>, both major[.minor]
    have=$1 want=$2
    case "$have" in *.*) ;; *) have="$have.0" ;; esac
    case "$want" in *.*) ;; *) want="$want.0" ;; esac
    hm=${have%%.*} hn=${have#*.}
    wm=${want%%.*} wn=${want#*.}
    [ "$hm" -gt "$wm" ] || { [ "$hm" -eq "$wm" ] && [ "$hn" -ge "$wn" ]; }
}

# --- finding tools --------------------------------------------------------------

# The Microsoft Store's app-execution aliases: a python.exe that opens the Store
# instead of running anything. Never executed, never recorded.
is_store_alias() {
    case "$1" in *[Ww]indows[Aa]pps/*|*[Ww]indows[Aa]pps\\*) return 0 ;; esac
    return 1
}

# Every executable called <name> on PATH, in PATH order, store aliases dropped.
on_path() {
    set -f
    old_ifs=$IFS
    IFS=:
    for d in $PATH; do
        [ -n "$d" ] || d=.
        for f in "$d/$1" "$d/$1.exe"; do
            if [ -f "$f" ] && [ -x "$f" ] && ! is_store_alias "$f"; then
                printf '%s\n' "$f"
            fi
        done
    done
    IFS=$old_ifs
    set +f
}

usable() { # <path>
    [ -n "$1" ] && [ -f "$1" ] && [ -x "$1" ] && ! is_store_alias "$1"
}

# Runs a Python candidate; prints "<major.minor>\n<sys.executable>".
probe_python() { # <path> [extra argument, e.g. -3 for py]
    if [ $# -gt 1 ]; then
        "$1" "$2" -c "$PYPROBE" 2>/dev/null | tr -d '\r'
    else
        "$1" -c "$PYPROBE" 2>/dev/null | tr -d '\r'
    fi
}

# The value recorded for <name> in .wikitool-tools.json, unescaped.
recorded() {
    [ -f "$TOOLS_FILE" ] || return 1
    value=$(sed -n "s/^ *\"$1\": *\"\(.*\)\",\{0,1\} *\$/\1/p" "$TOOLS_FILE" | head -n 1)
    [ -n "$value" ] || return 1
    printf '%s\n' "$value" | sed 's/\\"/"/g; s/\\\\/\\/g'
}

set_value() { # <name> -> the path given with --set, if any
    printf '%s\n' "$SETS" | sed -n "s/^$1=//p" | head -n 1
}

# --- --set: every named path has to work, or nothing is written -------------------

for entry in $(printf '%s\n' "$SETS" | sed -n 's/^\([^=]*\)=.*/\1/p'); do
    case " $TOOLS " in
        *" $entry "*) ;;
        *) echo "preflight: --set names '$entry', which is not a tool this platform needs:$TOOLS" >&2
           exit 1 ;;
    esac
done

# --- python -------------------------------------------------------------------------

PY="" PY_VERSION="" PY_OLD=""
PY_MIN=$(manifest_field tool python 3)

try_python() { # <path> [extra] -> sets PY/PY_VERSION on success, PY_OLD when too old
    out=$(probe_python "$@") || return 1
    version=$(printf '%s\n' "$out" | sed -n 1p)
    executable=$(printf '%s\n' "$out" | sed -n 2p)
    [ -n "$version" ] && [ -n "$executable" ] || return 1
    if version_ge "$version" "$PY_MIN"; then
        PY=$executable PY_VERSION=$version
        return 0
    fi
    PY_OLD="$version $1"
    return 1
}

python_extra() { # py and py.exe are the launcher: they need -3
    case "${1##*/}" in py|py.exe) printf '%s\n' -3 ;; esac
}

given=$(set_value python)
if [ -n "$given" ]; then
    extra=$(python_extra "$given")
    if ! usable "$given" || ! try_python "$given" $extra; then
        problem "The path given for Python does not work: $given" \
            "every wikitool command runs on Python $PY_MIN or newer, and this path did not start one" \
            "Check the path - it has to be the python executable itself, version $PY_MIN or newer.
Then run: $SELF --set python=<full path to python>"
        BAD_SET=1
    fi
else
    previous=$(recorded python) || previous=""
    if [ -n "$previous" ] && usable "$previous"; then
        try_python "$previous" || true
    fi
    if [ -z "$PY" ]; then
        if [ "$PLATFORM" = windows ]; then
            order="python: py:-3 python3:"
        else
            order="python3: python:"
        fi
        for candidate in $order; do
            name=${candidate%%:*}
            extra=${candidate#*:}
            found=$(on_path "$name")
            [ -n "$found" ] || continue
            # A here-document, not a pipe: `break 2` has to leave the outer loop
            # of this shell, and a path may contain spaces ("Program Files").
            while IFS= read -r path; do
                if [ -n "$extra" ]; then
                    try_python "$path" "$extra" && break 2
                else
                    try_python "$path" && break 2
                fi
            done <<EOF
$found
EOF
        done
    fi
fi

# --- the other tools --------------------------------------------------------------

REPORT=""
report() { # <status> <name> <version> <path>
    REPORT="$REPORT$(printf '%-8s %-7s %-8s %s' "$1" "$2" "$3" "$4")
"
}

if [ -n "$PY" ]; then
    report OK python "$PY_VERSION" "$PY"
    eval "FOUND_python=\$PY"
elif [ "$BAD_SET" -eq 0 ]; then
    label=$(manifest_field tool python 5)
    why=$(manifest_field tool python 6)
    if [ -n "$PY_OLD" ]; then
        report TOO_OLD python "${PY_OLD%% *}" "${PY_OLD#* }"
        problem "$label ${PY_OLD%% *} is too old - this stack needs $PY_MIN or newer." "$why" \
            "$(install_hint python)
Or, if a newer one is already installed, give its full path:
$SELF --set python=<full path to python>"
    else
        report MISSING python - -
        problem "$label $PY_MIN or newer was not found." "$why" \
            "$(install_hint python)
Or, if it is installed somewhere this check did not look, give its full path:
$SELF --set python=<full path to python>"
    fi
fi

for tool in $TOOLS; do
    [ "$tool" = python ] && continue
    label=$(manifest_field tool "$tool" 5)
    why=$(manifest_field tool "$tool" 6)
    minimum=$(manifest_field tool "$tool" 3)
    given=$(set_value "$tool")
    path=""
    if [ -n "$given" ]; then
        if usable "$given"; then
            path=$given
        else
            problem "The path given for $label does not work: $given" "$why" \
                "Check the path - it has to be the $tool executable itself.
Then run: $SELF --set $tool=<full path to $tool>"
            BAD_SET=1
            continue
        fi
    else
        previous=$(recorded "$tool") || previous=""
        if [ -n "$previous" ] && usable "$previous"; then
            path=$previous
        else
            path=$(on_path "$tool" | head -n 1)
        fi
    fi
    if [ -z "$path" ]; then
        report MISSING "$tool" - -
        problem "$label was not found." "$why" \
            "$(install_hint "$tool")
Or, if it is installed somewhere this check did not look, give its full path:
$SELF --set $tool=<full path to $tool>"
        continue
    fi
    version=$(version_of "$("$path" --version 2>/dev/null | tr -d '\r')")
    if [ "$minimum" != - ] && { [ -z "$version" ] || ! version_ge "$version" "$minimum"; }; then
        report TOO_OLD "$tool" "${version:-unknown}" "$path"
        problem "$label ${version:-of unknown version} is too old - this stack needs $minimum or newer." "$why" \
            "$(install_hint "$tool")"
        continue
    fi
    native=$(native_path "$path")
    report OK "$tool" "${version:--}" "$native"
    eval "FOUND_$tool=\$native"
done

# --- install folder length (Windows, long paths off) ------------------------------

if [ "$PLATFORM" = windows ] && ! longpaths_enabled; then
    limit=$(manifest_field limit install_dir_max 3)
    folder=$(native_path "$ROOT")
    length=$(utf16_length "$folder")
    if [ "$length" -gt "$limit" ]; then
        problem "The folder this wiki is installed in is too long ($length characters, at most $limit): $folder" \
            "Windows on this computer only allows paths of up to 259 characters, and the wiki's own files need the rest" \
            "Move the wiki to a shorter folder, for example C:\\Chemenu, and run this check there.
Alternatively, someone with administrator rights can turn on long paths in Windows."
    fi
fi

# --- record what was found ----------------------------------------------------------

json_string() {
    printf '%s' "$1" | sed 's/\\/\\\\/g; s/"/\\"/g'
}

write_tools_file() { # <true|false>
    tmp="$TOOLS_FILE.tmp.$$"
    {
        printf '{\n  "schema": 1,\n  "complete": %s,\n  "tools": {' "$1"
        separator=""
        for tool in $TOOLS; do
            eval "value=\${FOUND_$tool:-}"
            [ -n "$value" ] || continue
            printf '%s\n    "%s": "%s"' "$separator" "$tool" "$(json_string "$value")"
            separator=","
        done
        printf '\n  }\n}\n'
    } > "$tmp" && mv -f "$tmp" "$TOOLS_FILE"
}

printf '%s' "$REPORT"

if [ "$BAD_SET" -eq 1 ]; then
    stop                                  # nothing is written for a path that does not work
fi
write_tools_file false
if [ "$PROBLEMS" -gt 0 ]; then
    stop
fi

# --- tools/.venv ----------------------------------------------------------------------

venv_python() {
    if [ -x "$VENV/bin/python" ]; then
        printf '%s\n' "$VENV/bin/python"
    elif [ -f "$VENV/Scripts/python.exe" ]; then
        printf '%s\n' "$VENV/Scripts/python.exe"
    else
        return 1
    fi
}

last_lines() {
    printf '%s\n' "$1" | tail -n 5 | sed 's/^/  /'
}

VPY=$(venv_python) || VPY=""
if [ -z "$VPY" ] || ! "$VPY" -m pip --version >/dev/null 2>&1; then
    if ! output=$("$PY" -m venv --clear "$VENV" 2>&1) || ! VPY=$(venv_python); then
        fix="Python said:
$(last_lines "$output")"
        if [ "$PLATFORM" = linux ] && command -v apt-get >/dev/null 2>&1; then
            fix="sudo apt install python3-venv
$fix"
        fi
        problem "The wiki's own Python environment (tools/.venv) could not be created." \
            "wikitool runs in that environment, so that nothing it installs touches the rest of the computer" \
            "$fix"
        stop
    fi
fi

want=$("$VPY" -c 'import hashlib, sys; print(hashlib.sha256(open(sys.argv[1], "rb").read()).hexdigest())' \
    "$REQUIREMENTS" 2>/dev/null | tr -d '\r')
have=$(cat "$STAMP" 2>/dev/null) || have=""
if [ -z "$want" ] || [ "$want" != "$have" ]; then
    if ! output=$("$VPY" -m pip install --disable-pip-version-check --quiet -r "$REQUIREMENTS" 2>&1); then
        problem "The libraries wikitool needs could not be installed into tools/.venv." \
            "they are downloaded once from the internet; without them no wikitool command starts" \
            "Check that this computer can reach the internet (a proxy or a security program can block it; if so, ask whoever looks after this computer).
pip said:
$(last_lines "$output")"
        stop
    fi
    printf '%s\n' "$want" > "$STAMP"
fi
echo "OK       venv     -        $(native_path "$VENV")"

write_tools_file true
echo ""
echo "Preflight passed. Tool paths are recorded in .wikitool-tools.json; tools/wikitool is ready."
exit 0