package sqlite

import (
	"context"
	"database/sql"
	"fmt"
	"path/filepath"

	_ "modernc.org/sqlite" // SQLite driver

	"git.warky.dev/wdevs/relspecgo/pkg/models"
	"git.warky.dev/wdevs/relspecgo/pkg/readers"
)

// Reader implements the readers.Reader interface for SQLite databases
type Reader struct {
	options *readers.ReaderOptions
	db      *sql.DB
	ctx     context.Context
}

// NewReader creates a new SQLite reader
func NewReader(options *readers.ReaderOptions) *Reader {
	return &Reader{
		options: options,
		ctx:     context.Background(),
	}
}

// ReadDatabase reads the entire database schema from SQLite
func (r *Reader) ReadDatabase() (*models.Database, error) {
	// Validate file path or connection string
	dbPath := r.options.FilePath
	if dbPath == "" && r.options.ConnectionString != "" {
		dbPath = r.options.ConnectionString
	}
	if dbPath == "" {
		return nil, fmt.Errorf("file path or connection string is required")
	}

	// Connect to the database
	if err := r.connect(dbPath); err != nil {
		return nil, fmt.Errorf("failed to connect: %w", err)
	}
	defer r.close()

	// Get database name from file path
	dbName := filepath.Base(dbPath)
	if dbName == "" {
		dbName = "sqlite"
	}

	// Initialize database model
	db := models.InitDatabase(dbName)
	db.DatabaseType = models.SqlLiteDatabaseType
	db.SourceFormat = "sqlite"

	// Get SQLite version
	var version string
	err := r.db.QueryRowContext(r.ctx, "SELECT sqlite_version()").Scan(&version)
	if err == nil {
		db.DatabaseVersion = version
	}

	// SQLite doesn't have schemas, so we create a single "main" schema
	schema := models.InitSchema("main")
	schema.RefDatabase = db

	// Query tables
	tables, err := r.queryTables()
	if err != nil {
		return nil, fmt.Errorf("failed to query tables: %w", err)
	}
	schema.Tables = tables

	// Query views
	views, err := r.queryViews()
	if err != nil {
		return nil, fmt.Errorf("failed to query views: %w", err)
	}
	schema.Views = views

	// Query columns for tables and views
	for _, table := range schema.Tables {
		columns, err := r.queryColumns(table.Name)
		if err != nil {
			return nil, fmt.Errorf("failed to query columns for table %s: %w", table.Name, err)
		}
		table.Columns = columns
		table.RefSchema = schema

		// Query primary key
		pk, err := r.queryPrimaryKey(table.Name)
		if err != nil {
			return nil, fmt.Errorf("failed to query primary key for table %s: %w", table.Name, err)
		}
		if pk != nil {
			table.Constraints[pk.Name] = pk
			// Mark columns as primary key and not null
			for _, colName := range pk.Columns {
				if col, exists := table.Columns[colName]; exists {
					col.IsPrimaryKey = true
					col.NotNull = true
				}
			}
		}

		// Query foreign keys
		foreignKeys, err := r.queryForeignKeys(table.Name)
		if err != nil {
			return nil, fmt.Errorf("failed to query foreign keys for table %s: %w", table.Name, err)
		}
		for _, fk := range foreignKeys {
			table.Constraints[fk.Name] = fk
			// Derive relationship from foreign key
			r.deriveRelationship(table, fk)
		}

		// Query indexes
		indexes, err := r.queryIndexes(table.Name)
		if err != nil {
			return nil, fmt.Errorf("failed to query indexes for table %s: %w", table.Name, err)
		}
		for _, idx := range indexes {
			table.Indexes[idx.Name] = idx
		}
	}

	// Query columns for views
	for _, view := range schema.Views {
		columns, err := r.queryColumns(view.Name)
		if err != nil {
			return nil, fmt.Errorf("failed to query columns for view %s: %w", view.Name, err)
		}
		view.Columns = columns
		view.RefSchema = schema
	}

	// Add schema to database
	db.Schemas = append(db.Schemas, schema)

	return db, nil
}

// ReadSchema reads a single schema (returns the main schema from the database)
func (r *Reader) ReadSchema() (*models.Schema, error) {
	db, err := r.ReadDatabase()
	if err != nil {
		return nil, err
	}
	if len(db.Schemas) == 0 {
		return nil, fmt.Errorf("no schemas found in database")
	}
	return db.Schemas[0], nil
}

// ReadTable reads a single table (returns the first table from the schema)
func (r *Reader) ReadTable() (*models.Table, error) {
	schema, err := r.ReadSchema()
	if err != nil {
		return nil, err
	}
	if len(schema.Tables) == 0 {
		return nil, fmt.Errorf("no tables found in schema")
	}
	return schema.Tables[0], nil
}

// connect establishes a connection to the SQLite database
func (r *Reader) connect(dbPath string) error {
	db, err := sql.Open("sqlite", dbPath)
	if err != nil {
		return err
	}
	r.db = db
	return nil
}

// close closes the database connection
func (r *Reader) close() {
	if r.db != nil {
		r.db.Close()
	}
}

// mapDataType maps SQLite data types to canonical types
func (r *Reader) mapDataType(sqliteType string) string {
	// SQLite has a flexible type system, but we map common types
	typeMap := map[string]string{
		"INTEGER":  "int",
		"INT":      "int",
		"TINYINT":  "int8",
		"SMALLINT": "int16",
		"MEDIUMINT": "int",
		"BIGINT":   "int64",
		"UNSIGNED BIG INT": "uint64",
		"INT2":     "int16",
		"INT8":     "int64",
		"REAL":     "float64",
		"DOUBLE":   "float64",
		"DOUBLE PRECISION": "float64",
		"FLOAT":    "float32",
		"NUMERIC":  "decimal",
		"DECIMAL":  "decimal",
		"BOOLEAN":  "bool",
		"BOOL":     "bool",
		"DATE":     "date",
		"DATETIME": "timestamp",
		"TIMESTAMP": "timestamp",
		"TEXT":     "string",
		"VARCHAR":  "string",
		"CHAR":     "string",
		"CHARACTER": "string",
		"VARYING CHARACTER": "string",
		"NCHAR":    "string",
		"NVARCHAR": "string",
		"CLOB":     "text",
		"BLOB":     "bytea",
	}

	// Try exact match first
	if mapped, exists := typeMap[sqliteType]; exists {
		return mapped
	}

	// Try case-insensitive match for common types
	sqliteTypeUpper := sqliteType
	if len(sqliteType) > 0 {
		// Extract base type (e.g., "VARCHAR(255)" -> "VARCHAR")
		for baseType := range typeMap {
			if len(sqliteTypeUpper) >= len(baseType) && sqliteTypeUpper[:len(baseType)] == baseType {
				return typeMap[baseType]
			}
		}
	}

	// Default to string for unknown types
	return "string"
}

// deriveRelationship creates a relationship from a foreign key constraint
func (r *Reader) deriveRelationship(table *models.Table, fk *models.Constraint) {
	relationshipName := fmt.Sprintf("%s_to_%s", table.Name, fk.ReferencedTable)

	relationship := models.InitRelationship(relationshipName, models.OneToMany)
	relationship.FromTable = table.Name
	relationship.FromSchema = table.Schema
	relationship.ToTable = fk.ReferencedTable
	relationship.ToSchema = fk.ReferencedSchema
	relationship.ForeignKey = fk.Name

	// Store constraint actions in properties
	if fk.OnDelete != "" {
		relationship.Properties["on_delete"] = fk.OnDelete
	}
	if fk.OnUpdate != "" {
		relationship.Properties["on_update"] = fk.OnUpdate
	}

	table.Relationships[relationshipName] = relationship
}