#!/bin/sh

# Shared helpers for files that contain my-pi-owned blocks.
# Callers must provide say() and warn().

MY_PI_MANAGED_BACKUPS=${MY_PI_MANAGED_BACKUPS:-}

my_pi_backup_once() {
	managed_file=$1
	case "|$MY_PI_MANAGED_BACKUPS|" in
		*"|$managed_file|"*) return 0 ;;
	esac

	if [ -f "$managed_file" ]; then
		managed_backup=$(mktemp "$managed_file.my-pi-backup-$(date +%Y%m%d%H%M%S).XXXXXX") || return 1
		cp "$managed_file" "$managed_backup" || {
			rm -f "$managed_backup"
			return 1
		}
		say "已备份配置到 $managed_backup"
	fi
	MY_PI_MANAGED_BACKUPS=${MY_PI_MANAGED_BACKUPS:+$MY_PI_MANAGED_BACKUPS|}$managed_file
}

my_pi_managed_block_exists() {
	managed_file=$1
	managed_id=$2
	managed_begin="# >>> my-pi:$managed_id >>>"
	managed_end="# <<< my-pi:$managed_id <<<"
	[ -f "$managed_file" ] || return 1
	grep -F -x "$managed_begin" "$managed_file" >/dev/null 2>&1 &&
		grep -F -x "$managed_end" "$managed_file" >/dev/null 2>&1
}

my_pi_replace_managed_block() {
	managed_file=$1
	managed_id=$2
	managed_content_file=$3
	managed_placement=${4:-append}
	managed_anchor=${5:-}
	managed_begin="# >>> my-pi:$managed_id >>>"
	managed_end="# <<< my-pi:$managed_id <<<"
	managed_dir=${managed_file%/*}
	[ "$managed_dir" = "$managed_file" ] && managed_dir=.
	mkdir -p "$managed_dir" || return 1
	[ -f "$managed_file" ] || : > "$managed_file" || return 1

	managed_counts=$(awk -v begin="$managed_begin" -v end="$managed_end" '
		$0 == begin {
			begins++
			if (active) invalid = 1
			active = 1
		}
		$0 == end {
			ends++
			if (!active) invalid = 1
			active = 0
		}
		END {
			if (active) invalid = 1
			printf "%d %d %d\n", begins, ends, invalid
		}
	' "$managed_file") || return 1
	managed_begin_count=${managed_counts%% *}
	managed_remainder=${managed_counts#* }
	managed_end_count=${managed_remainder%% *}
	managed_invalid=${managed_remainder#* }
	if [ "$managed_begin_count" -ne "$managed_end_count" ] || \
		[ "$managed_begin_count" -gt 1 ] || [ "$managed_invalid" -ne 0 ]; then
		warn "$managed_file 中的 my-pi:$managed_id 受管标记不完整或重复，已拒绝修改。"
		return 1
	fi

	managed_tmp=$(mktemp "$managed_dir/.my-pi-managed.XXXXXX") || return 1
	if ! awk \
		-v begin="$managed_begin" \
		-v end="$managed_end" \
		-v content="$managed_content_file" \
		-v placement="$managed_placement" \
		-v anchor="$managed_anchor" '
		function emit_block(   line) {
			print begin
			while ((getline line < content) > 0) print line
			close(content)
			print end
		}
		BEGIN { replacing = 0; emitted = 0 }
		$0 == begin {
			emit_block()
			replacing = 1
			emitted = 1
			next
		}
		replacing && $0 == end { replacing = 0; next }
		replacing { next }
		!emitted && placement == "before" && anchor != "" && $0 ~ anchor {
			emit_block()
			emitted = 1
		}
		{ print }
		END {
			if (!emitted) {
				if (NR > 0) print ""
				emit_block()
			}
		}
	' "$managed_file" > "$managed_tmp"; then
		rm -f "$managed_tmp"
		return 1
	fi

	if cmp -s "$managed_tmp" "$managed_file"; then
		rm -f "$managed_tmp"
		return 0
	fi
	my_pi_backup_once "$managed_file" || {
		rm -f "$managed_tmp"
		return 1
	}
	if ! mv "$managed_tmp" "$managed_file"; then
		rm -f "$managed_tmp"
		return 1
	fi
}

my_pi_sync_managed_file() {
	managed_source=$1
	managed_target=$2
	[ -f "$managed_source" ] || {
		warn "找不到仓库配置：$managed_source"
		return 1
	}
	if [ -f "$managed_target" ] && cmp -s "$managed_source" "$managed_target"; then
		return 0
	fi

	managed_target_dir=${managed_target%/*}
	[ "$managed_target_dir" = "$managed_target" ] && managed_target_dir=.
	mkdir -p "$managed_target_dir" || return 1
	my_pi_backup_once "$managed_target" || return 1
	managed_tmp=$(mktemp "$managed_target_dir/.my-pi-sync.XXXXXX") || return 1
	if ! cp "$managed_source" "$managed_tmp" || ! mv "$managed_tmp" "$managed_target"; then
		rm -f "$managed_tmp"
		return 1
	fi
	say "已同步受管配置：$managed_target"
}