#!/bin/sh
# =============================================================================
# ZDDC shared build helpers — sourced by each tool's build.sh
#
# Usage in a tool build.sh:
#   root_dir=$(cd "$(dirname "$0")" && pwd)
#   . "$root_dir/../shared/build-lib.sh"
#
# Provides:
#   ensure_exists <path>          — abort with error if file missing
#   concat_files  <file ...>      — cat each relative path under $root_dir
#   build_timestamp               — ISO UTC timestamp string, set at source time;
#                                   used as build_label for dev builds
#   escape_js_close_tags <in> <out>
#                                 — copy <in> to <out> with all '</' rewritten as
#                                   '<\/' so the HTML parser cannot misread the
#                                   inlined JS as containing a closing </script>.
#                                   The JS engine treats \/ as a regular slash,
#                                   so runtime behaviour is unchanged.
#   compute_build_label <tool> [--release [<channel-or-version>]]
#                                 — sets globals: build_label, build_version,
#                                   is_release, is_red, channel.
#                                   See "Channels and release args" below.
#   promote_release <tool>        — for stable / alpha / beta, tag the
#                                   commit and upload the dist HTML as a
#                                   Codeberg release asset. No local mirror
#                                   under website/releases/ — the website
#                                   reverse-proxies download URLs to Codeberg
#                                   release-asset URLs. Stable cuts skip when
#                                   the tool's source is unchanged since the
#                                   latest stable tag.
#
# Channels and release args:
#   <none>            dev build, dist/ only, label
#                     "v<next-stable>-alpha · <ts> · <sha>[-dirty]" (red).
#                     No website/releases/ side-effect. To publish, re-run
#                     with `--release alpha`.
#   --release         stable, auto-bump patch from latest tag (or 0.0.1).
#                     Label "vX.Y.Z" (black). Tags + uploads.
#   --release X.Y.Z   stable, explicit version. Tags + uploads.
#   --release alpha   alpha channel cut at HEAD;
#                     label "v<next-stable>-alpha · <date> · <sha>" (red).
#                     Tags <tool>-vX.Y.Z-alpha.N + uploads.
#   --release beta    beta channel; label "v<next-stable>-beta · <date> · <sha>".
#                     Tags + uploads.
#   --release <other> error.
# =============================================================================

# Abort if root_dir is not set by the caller
if [ -z "${root_dir:-}" ]; then
    echo "build-lib.sh: root_dir must be set before sourcing this file" >&2
    exit 1
fi

# Pull in the Codeberg release-publish helper so promote_release can call
# its publish_codeberg_release function. Sourced unconditionally — the
# helper has no side effects when sourced (only defines functions).
. "$root_dir/../shared/publish-codeberg-release.sh"

# Fail hard on any missing source file
ensure_exists() {
    _path="$1"
    if [ ! -f "$_path" ]; then
        echo "error: missing file: $_path" >&2
        exit 1
    fi
}

# Concatenate files listed as positional args, each relative to root_dir
concat_files() {
    for _rel do
        ensure_exists "$root_dir/$_rel"
        cat "$root_dir/$_rel"
        printf '\n'
    done
}

# ISO UTC build timestamp — set once when this file is sourced
build_timestamp=$(date -u +"%Y-%m-%d %H:%M:%S")

# Read shared/favicon.svg, base64-encode it, and assemble a data: URI suitable
# for inlining into a <link rel="icon" type="image/svg+xml" href="..."> tag.
# Set once at source time so every tool's build.sh can pick it up via the
# $favicon_data_uri global. Editing shared/favicon.svg auto-propagates to all
# tools on the next build.
_favicon_path="$root_dir/../shared/favicon.svg"
if [ -f "$_favicon_path" ]; then
    favicon_data_uri="data:image/svg+xml;base64,$(base64 -w 0 "$_favicon_path")"
else
    favicon_data_uri=""
fi

# Rewrite '</script' (case-insensitive) in JS as '<\/script' so the HTML parser
# cannot mistake string contents for a closing </script> tag. Per the HTML5 spec
# only </script terminates a <script> block — other tags like </div> are safe
# inside a script's text content. Narrowly targeting </script avoids corrupting
# regex literals like /</g whose trailing letter is a flag, not a tag name.
# The JS engine treats '\/' the same as '/' inside a string, so behaviour is
# unchanged. See ARCHITECTURE.md "HTML Embedding Safety".
escape_js_close_tags() {
    sed 's#</\([sS][cC][rR][iI][pP][tT]\)#<\\/\1#g' "$1" > "$2"
}

# Echo the next pre-release version for a given channel + tag prefix.
#   next_prerelease <channel> <tag_prefix>
#
# Channel must be alpha or beta. Tag prefix is the leading text on this
# tool's stable git tags — e.g. "zddc-server-v" or "archive-v" — so the
# function can be called from either the server release script or any
# HTML tool's build.sh against the same monorepo tag namespace.
#
# Algorithm:
#   1. Walk tags matching <prefix>X.Y.Z (clean stable, no suffix); pick the
#      semver-highest. Default 0.0.0 if no stable tag exists yet.
#   2. Bump the patch component → next_patch.
#   3. Count existing tags of the form <prefix><next_patch>-<channel>.*
#      and emit <next_patch>-<channel>.<count+1>.
#
# The patch-bump assumption: every active pre-release window targets the
# next patch of the latest stable. Cutting a real stable resets the
# counter naturally because next_patch advances. Operators wanting a
# minor or major bump cut stable explicitly with a version arg, then the
# subsequent alphas auto-derive against the new stable.
next_prerelease() {
    _channel="$1"
    _prefix="$2"
    case "$_channel" in
        alpha | beta) ;;
        *) echo "next_prerelease: channel must be alpha or beta (got '$_channel')" >&2; return 1 ;;
    esac
    if [ -z "$_prefix" ]; then
        echo "next_prerelease: tag prefix is required" >&2
        return 1
    fi

    _latest=$(git -C "$root_dir" tag --list "${_prefix}*" 2>/dev/null \
              | grep -E "^${_prefix}[0-9]+\.[0-9]+\.[0-9]+\$" \
              | sed "s|^${_prefix}||" \
              | sort -V \
              | tail -1)
    [ -n "$_latest" ] || _latest="0.0.0"

    _major="${_latest%%.*}"
    _rest="${_latest#*.}"
    _minor="${_rest%%.*}"
    _patch="${_rest#*.}"
    _patch=$((_patch + 1))
    _next_patch="${_major}.${_minor}.${_patch}"

    _count=$(git -C "$root_dir" tag --list "${_prefix}${_next_patch}-${_channel}.*" 2>/dev/null | wc -l | tr -d ' ')
    _count=$((_count + 1))

    echo "${_next_patch}-${_channel}.${_count}"
}

# Validate that $1 is a strict X.Y.Z numeric version, where each component
# is a non-empty numeric string. Exits with an error if not.
_validate_semver() {
    _v="$1"
    _bad() {
        echo "error: invalid release argument: '$_v' (expected: alpha, beta, or X.Y.Z stable version)" >&2
        exit 1
    }
    _v1="${_v%%.*}"
    _rest="${_v#*.}"
    [ "$_rest" = "$_v" ] && _bad
    _v2="${_rest%%.*}"
    _v3="${_rest#*.}"
    { [ "$_v3" = "$_rest" ] || [ "$_v3" != "${_v3%.*}" ]; } && _bad
    case "$_v1" in '' | *[!0-9]*) _bad ;; esac
    case "$_v2" in '' | *[!0-9]*) _bad ;; esac
    case "$_v3" in '' | *[!0-9]*) _bad ;; esac
}

# Compute build label and channel. Reads positional args:
#   compute_build_label <tool_name> [--release [<channel-or-version>]]
# Sets global variables:
#   build_label    — text rendered into the page's {{BUILD_LABEL}} slot
#   build_version  — bare semver string (stable releases only)
#   is_release     — "1" for any --release invocation, else "0"
#   is_red         — "1" if the label should render red+bold (dev/alpha/beta), else "0"
#   channel        — "stable" / "alpha" / "beta" / "" (dev)
#
# Versioning: pre-release semver. The next-stable target is computed from
# the latest clean tool-vX.Y.Z tag (patch-bump). Plain builds and
# `--release alpha`/`--release beta` carry the next-stable target as a
# pre-release suffix in the on-page label so users can see which stable
# the alpha/beta is working toward. Stable releases write a clean
# vX.Y.Z label and tag.
#
# HTML tools do NOT tag alpha/beta cuts (consistent with current
# behavior — alpha and beta artifacts are mutable files, not immutable
# per-build snapshots). The label distinguishes plain dev builds from
# explicit channel cuts via the timestamp granularity (full ts + dirty
# marker for plain builds vs. date-only for `--release alpha|beta`).
compute_build_label() {
    _tool="$1"
    _flag="${2:-}"
    _arg="${3:-}"

    is_release=0
    is_red=1
    channel=""
    build_version=""

    # Compute the next-stable target once for label inclusion.
    _next_stable=$(_next_stable_for_tool "$_tool")

    if [ "$_flag" != "--release" ]; then
        # Plain builds are dev builds — labeled as the alpha channel because
        # that's what the next formal cut would produce, but no Codeberg upload
        # happens until `--release alpha` is invoked. Full timestamp (granular
        # than date) and -dirty marker distinguish iterative dev builds from
        # formal `--release alpha` cuts (which stamp date-only).
        _sha=$(git -C "$root_dir" rev-parse --short=7 HEAD 2>/dev/null || echo "unknown")
        if ! git -C "$root_dir" diff --quiet HEAD 2>/dev/null; then
            _sha="${_sha}-dirty"
        fi
        channel="alpha"
        build_label="v${_next_stable}-alpha · ${build_timestamp} · ${_sha}"
        return 0
    fi

    is_release=1

    case "$_arg" in
        alpha | beta)
            channel="$_arg"
            _date=$(date -u +"%Y-%m-%d")
            _sha=$(git -C "$root_dir" rev-parse --short=7 HEAD 2>/dev/null || echo "unknown")
            build_label="v${_next_stable}-${channel} · ${_date} · ${_sha}"
            return 0
            ;;
        '')
            # Stable cut, auto-bump patch.
            build_version="$_next_stable"
            ;;
        *)
            _validate_semver "$_arg"
            build_version="$_arg"
            ;;
    esac

    channel="stable"
    is_red=0
    build_label="v${build_version}"
}

# Compute the next-stable target version for a tool — i.e., the patch-bump
# of the latest clean <tool>-vX.Y.Z tag. Used by compute_build_label to
# embed the target version in alpha/beta labels.
_next_stable_for_tool() {
    _t="$1"
    _latest=$(git -C "$root_dir" tag --list "${_t}-v*" 2>/dev/null \
              | grep -E "^${_t}-v[0-9]+\.[0-9]+\.[0-9]+\$" \
              | sed "s|^${_t}-v||" \
              | sort -V \
              | tail -1)
    [ -n "$_latest" ] || _latest="0.0.0"
    _major="${_latest%%.*}"
    _rest="${_latest#*.}"
    _minor="${_rest%%.*}"
    _patch="${_rest#*.}"
    echo "${_major}.${_minor}.$((_patch + 1))"
}

# Promote a built dist file to a Codeberg release.
# Reads from caller scope: $channel, $build_version, $output_html, $root_dir.
#
# All three channels (alpha, beta, stable) follow the same shape now:
#   1. Compute the version (already done by compute_build_label for stable;
#      for alpha/beta we compute next_prerelease here).
#   2. Tag the commit <tool>-v<version> (or <tool>-v<version>-CHANNEL.N).
#   3. Upload the built dist HTML as a release asset to Codeberg.
#
# Idempotent: the publish helper replaces a same-named asset on re-upload,
# and the tag step is a no-op if the tag already points at HEAD.
#
# For stable: the original "skip if no source change since latest stable
# tag" guard still applies — pointless re-releases are silently no-op'd.
# For alpha/beta: the auto-incrementing counter already differentiates
# successive cuts, so no skip check.
#
# Requires $CODEBERG_TOKEN exported. publish_codeberg_release surfaces a
# clear error if it isn't.
promote_release() {
    _tool="$1"

    case "$channel" in
        stable)
            if [ -z "$build_version" ]; then
                echo "promote_release: stable channel but no build_version" >&2
                exit 1
            fi
            _latest=$(git -C "$root_dir" tag --list "${_tool}-v*" 2>/dev/null \
                      | grep -E "^${_tool}-v[0-9]+\.[0-9]+\.[0-9]+\$" \
                      | sort -V | tail -1)
            if [ -n "$_latest" ] && git -C "$root_dir" diff --quiet "$_latest" HEAD -- . ../shared 2>/dev/null; then
                echo "${_tool}: no source changes since $_latest — skipping"
                return 0
            fi
            _version="$build_version"
            ;;
        alpha | beta)
            _version=$(next_prerelease "$channel" "${_tool}-v")
            ;;
        *)
            echo "promote_release: unknown channel '$channel'" >&2
            exit 1
            ;;
    esac

    _tag="${_tool}-v${_version}"

    # Tag the commit (idempotent: skip if already at HEAD).
    if git -C "$root_dir" rev-parse -q --verify "refs/tags/$_tag" >/dev/null; then
        _existing=$(git -C "$root_dir" rev-list -n 1 "$_tag")
        _head=$(git -C "$root_dir" rev-parse HEAD)
        if [ "$_existing" != "$_head" ]; then
            echo "promote_release: tag $_tag already exists at $_existing, but HEAD is $_head" >&2
            return 1
        fi
        echo "(tag $_tag already at HEAD)"
    else
        git -C "$root_dir" tag "$_tag"
        echo "tagged $_tag"
    fi

    # Upload to Codeberg. The asset name embeds the version so consumers
    # can pin to a specific build (e.g. <tool>_v0.0.3-alpha.1.html).
    _asset="${_tool}_v${_version}.html"
    _staged="$root_dir/$_tool/dist/$_asset"
    cp "$output_html" "$_staged"
    if ! command -v publish_codeberg_release >/dev/null 2>&1; then
        # build-lib.sh is sourced before publish-codeberg-release.sh in the
        # canonical wrapper scripts; if the helper isn't loaded yet, bail
        # with a clear pointer.
        echo "promote_release: publish_codeberg_release not available; source shared/publish-codeberg-release.sh first" >&2
        return 1
    fi
    publish_codeberg_release "VARASYS/ZDDC" "$_tag" "$_staged"
    rm -f "$_staged"

    echo "Released $_tag (channel: $channel, version: $_version)"
    echo "  publish git tag with: git push origin $_tag"
}