#!/bin/sh

# Migrator script for gobin

set -e

MIGRATION_PATH="${MIGRATION_PATH:-./migrations}"

if [ -z "$DATABASE_URI" ]; then
  printf 'DATABASE_URI environment variable is not set\n'
  exit 1
fi

# Helper functions
run_sql() {
  psql "$@" "$DATABASE_URI"
}

is_migrated() {
  name="$1"

  printf '%s' "$migrations" | grep "$name" >/dev/null
}

apply_migration() {
  name="$1"

  if [ -z "$name" ]; then
    printf 'Usage: gobin-migrate apply NAME'
    exit
  fi

  if is_migrated "$name"; then
    printf '%s: already applied, skipping\n' "$name"
    return
  fi

  file="$MIGRATION_PATH/$name/up.sql"

  if [ ! -f "$file" ]; then
    printf 'Migration has not been found: %s\n' "$file"
    exit 1
  fi

  printf 'Applying migration %s\n' "$name"

  run_sql -f "$file" && \
    run_sql -c "insert into _gobin_migrations (name) values ('$name');" >/dev/null
}

revert_migration() {
  name="$1"

  if [ -z "$name" ]; then
    printf 'Usage: gobin-migrate revert NAME'
    exit
  fi

  if ! is_migrated "$name"; then
    printf '%s: not applied, skipping\n' "$name"
    return
  fi

  file="$MIGRATION_PATH/$name/down.sql"

  if [ ! -f "$file" ]; then
    printf 'Reverse migration has not been found: %s\n' "$file"
    exit 1
  fi

  printf 'Reverting migration %s\n' "$name"

  run_sql -f "$file" && \
    run_sql -c "delete from _gobin_migrations where name='$name';" >/dev/null
}

up_migrations() {
  for name in `ls "$MIGRATION_PATH"`; do
    apply_migration "$name"
  done
}

# Create migrations table
run_sql -c '
create table if not exists _gobin_migrations (
  name varchar(255) primary key,
  created_at timestamp default now()
);' 2>/dev/null >/dev/null

migrations="$(run_sql --csv -c 'select * from _gobin_migrations;' | \
  tail -n +2 | \
  awk -F',' '{ print $1 }')"

case "$1" in
  apply)
    shift 1

    apply_migration "$@"
    ;;
  revert)
    shift 1

    revert_migration "$@"
    ;;
  up)
    up_migrations
    ;;
  *)
    printf 'Usage: gobin-migrate <up|apply|revert> ARGUMENTS\n'
    ;;
esac