#!/usr/bin/env bash
# posts.sh - manage blog posts for kumardamani.net.
#
# A post is wired into four places, and this script keeps them in sync:
#   site.typ          metadata entry in site-info.pages ("post/<slug>": (...))
#   main.typ          #import line + #document block (label <post-<slug>>)
#   index.typ         - #pageref("post/<slug>") list item
#   post/<slug>.typ   the content file itself
#
# Run without arguments for an interactive menu, or use subcommands:
#   create, list, edit <slug>, update <slug> <field> [value], remove <slug>

set -euo pipefail
cd "$(dirname "$0")"

SITE=site.typ
MAIN=main.typ
INDEX=index.typ

die() { echo "error: $*" >&2; exit 1; }

usage() {
    cat <<'EOF'
Usage: posts.sh [command] [args]

Run without arguments for an interactive menu.

Commands:
  create                          Create a new post (interactive prompts),
                                  then open it in $EDITOR
  list                            List all posts (date, slug, title)
  edit <slug>                     Open an existing post in $EDITOR
  update <slug> <field> [value]   Update a field: title, long-title,
                                  description or date (prompts if no value)
  remove <slug>                   Remove a post: content file, metadata
                                  entry, and all page wiring
  help                            Show this help
EOF
}

# --- helpers ---------------------------------------------------------------

# Escape a string for use inside a Typst "..." string.
typst_escape() { printf '%s' "$1" | sed 's/\\/\\\\/g; s/"/\\"/g'; }

# Escape a string for use in a sed |s|...|...| replacement.
sed_escape() { printf '%s' "$1" | sed 's/[\\&|]/\\&/g'; }

slug_re='^[a-z0-9][a-z0-9-]*$'

get_slugs() { sed -n 's/^        "post\/\([a-z0-9-]*\)": ($/\1/p' "$SITE"; }

slug_exists() { grep -q '^        "post/'"$1"'": ($' "$SITE"; }

post_file() { [ -f "post/$1.typ" ]; }

prompt() { # prompt <varname> <text> [default]
    local var=$1 text=$2 default=${3:-} input
    if [ -n "$default" ]; then
        read -r -p "$text [$default]: " input || input=""
    else
        read -r -p "$text: " input || input=""
    fi
    printf -v "$var" '%s' "${input:-$default}"
}

confirm() { # confirm <question>
    local ans
    read -r -p "$1 [y/N]: " ans || ans=""
    [ "$ans" = "y" ] || [ "$ans" = "Y" ]
}

# Menu to pick a post slug; prints the choice on stdout.
pick_slug() {
    local slugs s
    mapfile -t slugs < <(get_slugs)
    [ ${#slugs[@]} -gt 0 ] || die "no posts found"
    select s in "${slugs[@]}"; do
        [ -n "$s" ] && { printf '%s' "$s"; return 0; }
    done
}

# Menu to pick a metadata field; prints the choice on stdout.
pick_field() {
    local f
    select f in title long-title description date; do
        [ -n "$f" ] && { printf '%s' "$f"; return 0; }
    done
}

# Insert the contents of file $3 before the first line matching regex $2
# in file $1. Falls back to appending (with a warning) if no match.
insert_before_first() {
    local file=$1 regex=$2 content=$3
    if awk -v f="$content" -v regex="$regex" '
        $0 ~ regex && !done {
            while ((getline l < f) > 0) print l
            close(f)
            done = 1
        }
        { print }
        END {
            if (!done) {
                while ((getline l < f) > 0) print l
                close(f)
                print "posts.sh: warning: anchor not found, appended at end" > "/dev/stderr"
            }
        }
    ' "$file" > "$file.tmp"; then
        mv "$file.tmp" "$file"
    else
        rm -f "$file.tmp"
        die "insert into $file failed"
    fi
}

# Rebuild the site to catch wiring mistakes early.
validate_build() {
    if ./build.sh >/dev/null 2>&1; then
        echo "site rebuild: OK"
    else
        echo "posts.sh: WARNING: site rebuild failed - run ./build.sh to see the errors" >&2
    fi
}

# --- commands --------------------------------------------------------------

cmd_list() {
    awk '
        BEGIN { printf "%-10s  %-24s  %s\n", "DATE", "SLUG", "TITLE" }
        /^        "post\/[a-z0-9-]+": \($/ {
            slug = $0
            sub(/^ *"post\//, "", slug); sub(/": \($/, "", slug)
            title = date = ""
        }
        slug != "" && /^            title: "/ {
            title = $0; sub(/^ *title: "/, "", title); sub(/",$/, "", title)
        }
        slug != "" && /^            date: "/ {
            date = $0; sub(/^ *date: "/, "", date); sub(/",$/, "", date)
        }
        /^        \),$/ && slug != "" {
            printf "%-10s  %-24s  %s\n", date, slug, title
            slug = ""
        }
    ' "$SITE"
}

cmd_create() {
    local title slug long_title desc date
    prompt title "Title"
    [ -n "$title" ] || die "title is required"

    local default_slug
    default_slug=$(printf '%s' "$title" | tr 'A-Z' 'a-z' | sed 's/[^a-z0-9]\+/-/g; s/^-\+//; s/-\+$//')
    prompt slug "Slug" "$default_slug"
    [[ "$slug" =~ $slug_re ]] || die "invalid slug '$slug' (use lowercase letters, digits, dashes)"
    slug_exists "$slug" && die "post '$slug' already exists in $SITE"
    post_file "$slug" && die "post/$slug.typ already exists"

    prompt long_title "Long title (blank = same as title)" "$title"
    prompt desc "Description"
    [ -n "$desc" ] || die "description is required"
    prompt date "Date" "$(date +%F)"
    [[ "$date" =~ ^[0-9]{4}-[0-9]{2}-[0-9]{2}$ ]] || die "invalid date '$date' (want YYYY-MM-DD)"

    echo
    echo "  slug:        $slug"
    echo "  title:       $title"
    echo "  long title:  $long_title"
    echo "  description: $desc"
    echo "  date:        $date"
    echo
    confirm "Create this post?" || die "aborted"

    local e_title e_long e_desc
    e_title=$(typst_escape "$title")
    e_long=$(typst_escape "$long_title")
    e_desc=$(typst_escape "$desc")

    # 1. content file from template
    mkdir -p "post/$slug"
    cat > "post/$slug.typ" <<EOF
#import "/global/common.typ": *

#let doc = [
= First heading

Start writing here.
// Put images in post/$slug/ and embed them with:
// #fig("$slug/file.webp", alt: "description", caption: [a caption]).
]
EOF

    # 2. metadata entry in site.typ (posts are newest-first, so it goes
    #    right after the contact entry, at the top of the posts section)
    local tmp
    tmp=$(mktemp)
    {
        echo "        \"post/$slug\": ("
        echo "            title: \"$e_title\","
        [ "$long_title" = "$title" ] || echo "            long-title: \"$e_long\","
        echo "            date: \"$date\","
        echo "            description: \"$e_desc\","
        echo "            hidden: true,"
        echo "        ),"
    } > "$tmp"
    sed -i '/^        contact: (title: "Contact"),$/r '"$tmp" "$SITE"
    rm -f "$tmp"

    # 3. import + document block in main.typ (newest first)
    tmp=$(mktemp)
    echo "#import \"/post/$slug.typ\" as post-$slug" > "$tmp"
    insert_before_first "$MAIN" '^#import "/post/' "$tmp"
    {
        echo "#document(\"post/$slug.html\", title: title-for(\"post/$slug\"))["
        echo "    #post-page(\"post/$slug\", site-info, post-$slug.doc)"
        echo "] <post-$slug>"
        echo
    } > "$tmp"
    insert_before_first "$MAIN" '^#document[(]"post/' "$tmp"
    rm -f "$tmp"

    # 4. index page listing (newest first)
    tmp=$(mktemp)
    echo "- #pageref(\"post/$slug\")" > "$tmp"
    insert_before_first "$INDEX" '^- #pageref[(]"post/' "$tmp"
    rm -f "$tmp"

    echo "created post/$slug.typ"
    validate_build

    "${EDITOR:-vi}" "post/$slug.typ"
}

cmd_edit() {
    local slug=${1:-}
    [ -n "$slug" ] || die "usage: posts.sh edit <slug>"
    post_file "$slug" || die "no such post: $slug"
    "${EDITOR:-vi}" "post/$slug.typ"
}

cmd_update() {
    local slug=${1:-} field=${2:-} value=${3:-}
    [ -n "$slug" ] && [ -n "$field" ] || die "usage: posts.sh update <slug> <field> [value]"
    slug_exists "$slug" || die "no such post: $slug"
    case "$field" in
        title|long-title|description|date) ;;
        *) die "unknown field '$field' (want: title, long-title, description, date)" ;;
    esac

    local range='/^        "post\/'"$slug"'": ($/,/^        ),$/'
    local current
    current=$(sed -n "${range}p" "$SITE" | sed -n 's/^            '"$field"': "\(.*\)",$/\1/p')

    if [ -z "$value" ]; then
        prompt value "New $field" "$current"
    fi
    [ -n "$value" ] || die "empty value"
    if [ "$field" = date ]; then
        [[ "$value" =~ ^[0-9]{4}-[0-9]{2}-[0-9]{2}$ ]] || die "invalid date '$value' (want YYYY-MM-DD)"
    fi

    local esc
    esc=$(sed_escape "$(typst_escape "$value")")

    if [ -n "$current" ]; then
        sed -i "${range}s|^            $field: \".*\",\$|            $field: \"$esc\",|" "$SITE"
    else
        # field absent (e.g. long-title): add it after the title line
        sed -i "${range}s|^            title: \".*\",\$|&\n            $field: \"$esc\",|" "$SITE"
    fi

    # verify the edit actually landed
    local newval
    newval=$(sed -n "${range}p" "$SITE" | sed -n 's/^            '"$field"': "\(.*\)",$/\1/p')
    [ "$newval" = "$(typst_escape "$value")" ] || die "failed to update $field in $SITE"

    echo "updated $slug: $field = \"$value\""
    if [ "$field" = title ] && sed -n "${range}p" "$SITE" | grep -q '^            long-title: '; then
        echo "house-keeping note: $slug also has a long-title - update it too if it should change"
    fi
    validate_build
}

cmd_remove() {
    local slug=${1:-}
    [ -n "$slug" ] || die "usage: posts.sh remove <slug>"
    slug_exists "$slug" || die "no such post: $slug"

    local title
    title=$(sed -n '/^        "post\/'"$slug"'": ($/,/^        ),$/p' "$SITE" \
        | sed -n 's/^            title: "\(.*\)",$/\1/p')
    echo "about to remove: $slug - $title"
    confirm "Really remove '$slug'?" || die "aborted"

    # metadata entry (fixed-shape block: key line through the closing "),")
    sed -i '/^        "post\/'"$slug"'": ($/,/^        ),$/d' "$SITE"
    # import line + document block (through the blank line that follows it)
    sed -i '/^#import "\/post\/'"$slug"'\.typ" as /d' "$MAIN"
    sed -i '/^#document("post\/'"$slug"'\.html"/,/^$/d' "$MAIN"
    # index listing
    sed -i '/^- #pageref("post\/'"$slug"'")$/d' "$INDEX"

    rm -f "post/$slug.typ"
    if [ -d "post/$slug" ]; then
        if confirm "also delete image directory post/$slug/?"; then
            rm -r "post/$slug"
            echo "deleted post/$slug/"
        fi
    fi

    echo "removed $slug"
    validate_build
}

# --- interactive menu --------------------------------------------------------

interactive() {
    local cmd
    echo "posts.sh - blog post management"
    select cmd in create list edit update remove quit; do
        case "$cmd" in
            create) cmd_create ;;
            list)   cmd_list ;;
            edit)   cmd_edit "$(pick_slug)" ;;
            update) cmd_update "$(pick_slug)" "$(pick_field)" ;;
            remove) cmd_remove "$(pick_slug)" ;;
            quit)   break ;;
            *)      continue ;;
        esac
    done
}

# --- dispatch ----------------------------------------------------------------

case ${1:-} in
    "") interactive ;;
    create) shift; cmd_create "$@" ;;
    list|ls) shift; cmd_list "$@" ;;
    edit) shift; cmd_edit "$@" ;;
    update) shift; cmd_update "$@" ;;
    remove|rm) shift; cmd_remove "$@" ;;
    help|-h|--help) usage ;;
    *) usage >&2; exit 1 ;;
esac