package orm

import (
	"context"
	"fmt"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgconn"
	"github.com/jackc/pgx/v5/pgxpool"
	"io"
	"log/slog"
	"os"
	"rockfic.com/orm/internal/logging"
	"time"
)

// LevelQuery enables logging of SQL queries if passed to Config.LogLevel
const LevelQuery = slog.Level(-6)
const defaultKey = "default"

type Config struct {
	DryRun   bool       // when true, queries will not run on the underlying database
	LogLevel slog.Level // controls the level of information logged; defaults to slog.LevelInfo if not set
	LogTo    io.Writer  // where to write log output to; defaults to os.Stdout
}

type Engine struct {
	modelMap *internalModelMap
	conn     *pgxpool.Pool
	m2mSeen  map[string]bool
	dryRun   bool
	pgCfg    *pgxpool.Config
	ctx      context.Context
	logger   *slog.Logger
	cfg      *Config
	levelVar *slog.LevelVar
	connStr  string
}

// Models - parse and register one or more types as persistable models
func (e *Engine) Models(v ...any) {
	emm := makeModelMap(v...)
	for k := range emm.Map {
		if _, ok := e.modelMap.Map[k]; !ok {
			e.modelMap.Mux.Lock()
			e.modelMap.Map[k] = emm.Map[k]
			e.modelMap.Mux.Unlock()
		}
	}
}

// Model - createes a Query and sets its model to
// the one corresponding to the type of `val`
func (e *Engine) Model(val any) *Query {
	qq := &Query{
		engine:         e,
		ctx:            context.Background(),
		wheres:         make(map[string][]any),
		orders:         make([]string, 0),
		populationTree: make(map[string]any),
		joins:          make([]string, 0),
	}
	return qq.setModel(val)
}

// QueryRaw - wrapper for the Query method of pgxpool.Pool
func (e *Engine) QueryRaw(sql string, args ...any) (pgx.Rows, error) {
	return e.conn.Query(e.ctx, sql, args...)
}

// Migrate - non-destructive; run migrations to update the underlying schema, WITHOUT dropping tables beforehand
func (e *Engine) Migrate() error {
	failedMigrations := make(map[string]*Model)
	var err error
	for mk, m := range e.modelMap.Map {
		err = m.migrate(e)
		if err != nil {
			failedMigrations[mk] = m
		}
	}

	for len(failedMigrations) > 0 {
		e.m2mSeen = make(map[string]bool)
		for mk, m := range failedMigrations {
			err = m.migrate(e)
			if err == nil {
				delete(failedMigrations, mk)
			}
		}
	}
	return err
}

// MigrateDropping - destructive migration; DROP the necessary tables if they exist,
// then recreate them to match your models' schema
func (e *Engine) MigrateDropping() error {
	for _, m := range e.modelMap.Map {
		sql := fmt.Sprintf("DROP TABLE IF EXISTS %s CASCADE;", m.TableName)
		if _, err := e.conn.Exec(e.ctx, sql); err != nil {
			return err
		}
		for _, r := range m.Relationships {
			if r.m2mIsh() || r.Type == ManyToMany {
				jsql := fmt.Sprintf("DROP TABLE IF EXISTS %s CASCADE;", r.ComputeJoinTable())
				if _, err := e.conn.Exec(e.ctx, jsql); err != nil {
					return err
				}
			}
		}
	}
	return e.Migrate()
}

func (e *Engine) logQuery(msg, sql string, args []any) {
	e.logger.Log(e.ctx, LevelQuery, msg, "sql", sql, "args", logTrunc(200, args))
}

func (e *Engine) logSql(msg, sql string) {
	e.logger.Log(e.ctx, LevelQuery, msg, "sql", sql)
}

// Disconnect - closes and disposes of this Engine's connection pool.
func (e *Engine) Disconnect() {
	e.conn.Close()
	if asFile, ok := e.cfg.LogTo.(*os.File); ok {
		_ = asFile.Close()
	}
}

// Open - creates a new connection according to `connString`
// and returns a brand new Engine to run FUCK operations on.
func Open(connString string, cfg *Config) (*Engine, error) {
	if cfg == nil {
		cfg = &Config{
			LogLevel: slog.LevelInfo,
			LogTo:    os.Stdout,
			DryRun:   connString == "",
		}
	} else {
		if cfg.LogTo == nil {
			cfg.LogTo = os.Stdout
		}
	}
	e := &Engine{
		modelMap: &internalModelMap{
			Map: make(map[string]*Model),
		},
		m2mSeen:  make(map[string]bool),
		dryRun:   connString == "",
		ctx:      context.Background(),
		levelVar: new(slog.LevelVar),
		cfg:      cfg,
	}
	e.levelVar.Set(cfg.LogLevel)
	replacer := func(groups []string, a slog.Attr) slog.Attr {
		if a.Key == slog.LevelKey {
			level := a.Value.Any().(slog.Level)
			switch level {
			case LevelQuery:
				a.Value = slog.StringValue("query")
			}
		}
		return a
	}
	e.logger = slog.New(logging.NewFormattedHandler(cfg.LogTo, logging.Options{
		Level:       e.levelVar,
		ReplaceAttr: replacer,
		Format:      "{{.Time}} [{{.Level}}] {{.Message}} | {{ rest }}",
	}))
	slog.SetDefault(e.logger)
	if connString != "" {
		engines.Mux.Lock()
		if len(engines.Engines) == 0 || engines.Engines[defaultKey] == nil {
			engines.Engines[defaultKey] = e
		} else {
			engines.Engines[connString] = e
		}
		e.connStr = ""
		engines.Mux.Unlock()
		var err error
		e.pgCfg, err = pgxpool.ParseConfig(connString)
		e.pgCfg.MinConns = 5
		e.pgCfg.MaxConns = 10
		e.pgCfg.MaxConnIdleTime = time.Minute * 2
		e.pgCfg.AfterConnect = func(ctx context.Context, conn *pgx.Conn) error {
			oldHandler := conn.Config().OnPgError
			conn.Config().OnPgError = func(conn *pgconn.PgConn, pgError *pgconn.PgError) bool {
				e.logger.Error("ERROR ->", "err", pgError.Error())
				return oldHandler(conn, pgError)
			}
			return nil
		}
		if err != nil {
			return nil, err
		}
		e.conn, err = pgxpool.NewWithConfig(e.ctx, e.pgCfg)
		if err != nil {
			return nil, err
		}
	}
	return e, nil
}