package dctx

import (
	"encoding/xml"
	"fmt"
	"os"
	"strings"

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

// Reader implements the readers.Reader interface for DCTX format
type Reader struct {
	options *readers.ReaderOptions
}

// NewReader creates a new DCTX reader with the given options
func NewReader(options *readers.ReaderOptions) *Reader {
	return &Reader{
		options: options,
	}
}

// ReadDatabase reads and parses DCTX input, returning a Database model
func (r *Reader) ReadDatabase() (*models.Database, error) {
	if r.options.FilePath == "" {
		return nil, fmt.Errorf("file path is required for DCTX reader")
	}

	data, err := os.ReadFile(r.options.FilePath)
	if err != nil {
		return nil, fmt.Errorf("failed to read file: %w", err)
	}

	var dctx models.DCTXDictionary
	if err := xml.Unmarshal(data, &dctx); err != nil {
		return nil, fmt.Errorf("failed to parse DCTX XML: %w", err)
	}

	return r.convertToDatabase(&dctx)
}

// ReadSchema reads and parses DCTX input, returning a Schema model
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 DCTX")
	}

	return db.Schemas[0], nil
}

// ReadTable reads and parses DCTX input, returning a Table model
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 DCTX")
	}

	return schema.Tables[0], nil
}

// convertToDatabase converts a DCTX dictionary to a Database model
func (r *Reader) convertToDatabase(dctx *models.DCTXDictionary) (*models.Database, error) {
	dbName := dctx.Name
	if dbName == "" {
		dbName = "database"
	}

	db := models.InitDatabase(dbName)
	schema := models.InitSchema("public")

	// Create GUID mappings for tables and keys
	tableGuidMap := make(map[string]string)             // GUID -> table name
	keyGuidMap := make(map[string]*models.DCTXKey)      // GUID -> key definition
	keyTableMap := make(map[string]string)              // key GUID -> table name
	fieldGuidMaps := make(map[string]map[string]string) // table name -> field GUID -> field name

	// First pass: build GUID mappings
	for i := range dctx.Tables {
		dctxTable := &dctx.Tables[i]
		if !r.hasSQLOption(dctxTable) {
			continue
		}

		tableName := r.sanitizeName(dctxTable.Name)
		tableGuidMap[dctxTable.Guid] = tableName

		// Map keys to their table
		for _, dctxKey := range dctxTable.Keys {
			keyGuidMap[dctxKey.Guid] = &dctxKey
			keyTableMap[dctxKey.Guid] = tableName
		}
	}

	// Process tables - only include tables with SQL option enabled
	for i := range dctx.Tables {
		dctxTable := &dctx.Tables[i]
		if !r.hasSQLOption(dctxTable) {
			continue
		}

		table, fieldGuidMap, err := r.convertTable(dctxTable)
		if err != nil {
			return nil, fmt.Errorf("failed to convert table %s: %w", dctxTable.Name, err)
		}

		fieldGuidMaps[table.Name] = fieldGuidMap
		schema.Tables = append(schema.Tables, table)

		// Process keys (indexes, primary keys)
		err = r.processKeys(dctxTable, table, fieldGuidMap)
		if err != nil {
			return nil, fmt.Errorf("failed to process keys for table %s: %w", dctxTable.Name, err)
		}
	}

	// Process relations
	err := r.processRelations(dctx, schema, tableGuidMap, keyGuidMap, fieldGuidMaps)
	if err != nil {
		return nil, fmt.Errorf("failed to process relations: %w", err)
	}

	db.Schemas = append(db.Schemas, schema)
	return db, nil
}

// hasSQLOption checks if a DCTX table has the SQL option set to "1"
func (r *Reader) hasSQLOption(dctxTable *models.DCTXTable) bool {
	for _, option := range dctxTable.Options {
		if option.Property == "SQL" && option.PropertyValue == "1" {
			return true
		}
	}
	return false
}

// collectFieldGuids recursively collects all field GUIDs from a field and its nested fields
func (r *Reader) collectFieldGuids(dctxField *models.DCTXField, guidMap map[string]string) {
	// Store the current field's GUID if available
	if dctxField.Guid != "" && dctxField.Name != "" {
		guidMap[dctxField.Guid] = r.sanitizeName(dctxField.Name)
	}

	// Recursively process nested fields (for GROUP types)
	for i := range dctxField.Fields {
		r.collectFieldGuids(&dctxField.Fields[i], guidMap)
	}
}

// convertTable converts a DCTX table to a Table model
func (r *Reader) convertTable(dctxTable *models.DCTXTable) (*models.Table, map[string]string, error) {
	tableName := r.sanitizeName(dctxTable.Name)
	table := models.InitTable(tableName, "public")
	table.Description = dctxTable.Description

	fieldGuidMap := make(map[string]string)

	// Process fields
	for _, dctxField := range dctxTable.Fields {
		// Recursively collect all field GUIDs (including nested fields in GROUP types)
		r.collectFieldGuids(&dctxField, fieldGuidMap)

		columns, err := r.convertField(&dctxField, table.Name)
		if err != nil {
			return nil, nil, fmt.Errorf("failed to convert field %s: %w", dctxField.Name, err)
		}

		// Add all columns
		for _, column := range columns {
			table.Columns[column.Name] = column
		}
	}

	return table, fieldGuidMap, nil
}

// convertField converts a DCTX field to Column(s)
func (r *Reader) convertField(dctxField *models.DCTXField, tableName string) ([]*models.Column, error) {
	var columns []*models.Column

	// Handle GROUP fields (nested structures)
	if dctxField.DataType == "GROUP" {
		for _, subField := range dctxField.Fields {
			subColumns, err := r.convertField(&subField, tableName)
			if err != nil {
				return nil, err
			}
			columns = append(columns, subColumns...)
		}
		return columns, nil
	}

	// Convert single field
	column := models.InitColumn(r.sanitizeName(dctxField.Name), tableName, "public")

	// Map Clarion data types
	dataType, length := r.mapDataType(dctxField.DataType, dctxField.Size)
	column.Type = dataType
	column.Length = length

	// Check for auto-increment (identity)
	for _, option := range dctxField.Options {
		if option.Property == "IsIdentity" && option.PropertyValue == "1" {
			column.AutoIncrement = true
			column.NotNull = true
		}
	}

	columns = append(columns, column)
	return columns, nil
}

// mapDataType maps Clarion data types to SQL types
func (r *Reader) mapDataType(clarionType string, size int) (sqlType string, precision int) {
	switch strings.ToUpper(clarionType) {
	case "LONG":
		if size == 8 {
			return "bigint", 0
		}
		return "integer", 0

	case "ULONG":
		if size == 8 {
			return "bigint", 0
		}
		return "integer", 0

	case "SHORT":
		return "smallint", 0

	case "USHORT":
		return "smallint", 0

	case "BYTE":
		return "smallint", 0

	case "STRING":
		if size > 0 {
			return "varchar", size
		}
		return "text", 0

	case "CSTRING":
		if size > 0 {
			// CSTRING includes null terminator, so subtract 1
			length := size - 1
			if length <= 0 {
				length = 1
			}
			return "varchar", length
		}
		return "text", 0

	case "PSTRING":
		if size > 0 {
			return "varchar", size
		}
		return "text", 0

	case "DECIMAL":
		return "decimal", 0

	case "REAL":
		return "real", 0

	case "SREAL":
		return "double precision", 0

	case "DATE":
		return "date", 0

	case "TIME":
		return "time", 0

	case "BLOB":
		return "bytea", 0

	case "MEMO":
		return "text", 0

	case "BOOL", "BOOLEAN":
		return "boolean", 0

	default:
		return "text", 0
	}
}

// processKeys processes DCTX keys and converts them to indexes and primary keys
func (r *Reader) processKeys(dctxTable *models.DCTXTable, table *models.Table, fieldGuidMap map[string]string) error {
	for _, dctxKey := range dctxTable.Keys {
		err := r.convertKey(&dctxKey, table, fieldGuidMap)
		if err != nil {
			return fmt.Errorf("failed to convert key %s: %w", dctxKey.Name, err)
		}
	}
	return nil
}

// convertKey converts a DCTX key to appropriate constraint/index
func (r *Reader) convertKey(dctxKey *models.DCTXKey, table *models.Table, fieldGuidMap map[string]string) error {
	var columns []string

	// Extract column names from key components
	if len(dctxKey.Components) > 0 {
		for _, component := range dctxKey.Components {
			if fieldName, exists := fieldGuidMap[component.FieldId]; exists {
				columns = append(columns, fieldName)
			}
		}
	}

	// If no columns found, try to infer
	if len(columns) == 0 {
		if dctxKey.Primary {
			// Look for common primary key column patterns
			for colName := range table.Columns {
				colNameLower := strings.ToLower(colName)
				if strings.HasPrefix(colNameLower, "rid_") || strings.HasSuffix(colNameLower, "id") {
					columns = append(columns, colName)
					break
				}
			}
		}

		// If still no columns, skip
		if len(columns) == 0 {
			return nil
		}
	}

	// Handle primary key
	if dctxKey.Primary {
		// Create primary key constraint
		constraint := models.InitConstraint(r.sanitizeName(dctxKey.Name), models.PrimaryKeyConstraint)
		constraint.Table = table.Name
		constraint.Schema = table.Schema
		constraint.Columns = columns

		table.Constraints[constraint.Name] = constraint

		// Mark columns as NOT NULL
		for _, colName := range columns {
			if col, exists := table.Columns[colName]; exists {
				col.NotNull = true
				col.IsPrimaryKey = true
			}
		}
		return nil
	}

	// Handle regular index
	index := models.InitIndex(r.sanitizeName(dctxKey.Name), table.Name, table.Schema)
	index.Table = table.Name
	index.Schema = table.Schema
	index.Columns = columns
	index.Unique = dctxKey.Unique
	index.Type = "btree"

	table.Indexes[index.Name] = index
	return nil
}

// processRelations processes DCTX relations and creates foreign keys
func (r *Reader) processRelations(dctx *models.DCTXDictionary, schema *models.Schema, tableGuidMap map[string]string, keyGuidMap map[string]*models.DCTXKey, fieldGuidMaps map[string]map[string]string) error {
	for i := range dctx.Relations {
		relation := &dctx.Relations[i]
		// Get table names from GUIDs
		primaryTableName := tableGuidMap[relation.PrimaryTable]
		foreignTableName := tableGuidMap[relation.ForeignTable]

		if primaryTableName == "" || foreignTableName == "" {
			continue
		}

		// Find tables
		var primaryTable, foreignTable *models.Table
		for _, table := range schema.Tables {
			if table.Name == primaryTableName {
				primaryTable = table
			}
			if table.Name == foreignTableName {
				foreignTable = table
			}
		}

		if primaryTable == nil || foreignTable == nil {
			continue
		}

		var fkColumns, pkColumns []string

		// Try to use explicit field mappings
		// NOTE: DCTX format has backwards naming - ForeignMapping contains primary table fields,
		// and PrimaryMapping contains foreign table fields
		if len(relation.ForeignMappings) > 0 && len(relation.PrimaryMappings) > 0 {
			foreignFieldMap := fieldGuidMaps[foreignTableName]
			primaryFieldMap := fieldGuidMaps[primaryTableName]

			// ForeignMapping actually contains fields from the PRIMARY table
			for _, mapping := range relation.ForeignMappings {
				if fieldName, exists := primaryFieldMap[mapping.Field]; exists {
					pkColumns = append(pkColumns, fieldName)
				}
			}

			// PrimaryMapping actually contains fields from the FOREIGN table
			for _, mapping := range relation.PrimaryMappings {
				if fieldName, exists := foreignFieldMap[mapping.Field]; exists {
					fkColumns = append(fkColumns, fieldName)
				}
			}
		}

		// Validate columns exist
		if len(fkColumns) == 0 || len(pkColumns) == 0 {
			continue
		}

		allFkColumnsExist := true
		for _, colName := range fkColumns {
			if _, exists := foreignTable.Columns[colName]; !exists {
				allFkColumnsExist = false
				break
			}
		}
		if !allFkColumnsExist {
			continue
		}

		allPkColumnsExist := true
		for _, colName := range pkColumns {
			if _, exists := primaryTable.Columns[colName]; !exists {
				allPkColumnsExist = false
				break
			}
		}
		if !allPkColumnsExist {
			continue
		}

		// Create foreign key
		fkName := r.sanitizeName(fmt.Sprintf("fk_%s_%s", foreignTableName, primaryTableName))
		constraint := models.InitConstraint(fkName, models.ForeignKeyConstraint)
		constraint.Table = foreignTableName
		constraint.Schema = "public"
		constraint.Columns = fkColumns
		constraint.ReferencedTable = primaryTableName
		constraint.ReferencedSchema = "public"
		constraint.ReferencedColumns = pkColumns
		constraint.OnDelete = r.mapReferentialAction(relation.Delete)
		constraint.OnUpdate = r.mapReferentialAction(relation.Update)

		foreignTable.Constraints[fkName] = constraint

		// Create relationship
		relationshipName := fmt.Sprintf("%s_to_%s", foreignTableName, primaryTableName)
		relationship := models.InitRelationship(relationshipName, models.OneToMany)
		relationship.FromTable = primaryTableName
		relationship.FromSchema = "public"
		relationship.ToTable = foreignTableName
		relationship.ToSchema = "public"
		relationship.ForeignKey = fkName
		relationship.Properties["on_delete"] = constraint.OnDelete
		relationship.Properties["on_update"] = constraint.OnUpdate

		foreignTable.Relationships[relationshipName] = relationship
	}

	return nil
}

// mapReferentialAction maps DCTX referential actions to SQL syntax
func (r *Reader) mapReferentialAction(action string) string {
	switch strings.ToUpper(action) {
	case "RESTRICT", "RESTRICT_SERVER":
		return "RESTRICT"
	case "CASCADE", "CASCADE_SERVER":
		return "CASCADE"
	case "SET_NULL", "SET_NULL_SERVER":
		return "SET NULL"
	case "SET_DEFAULT", "SET_DEFAULT_SERVER":
		return "SET DEFAULT"
	case "NO_ACTION", "NO_ACTION_SERVER":
		return "NO ACTION"
	default:
		return "RESTRICT"
	}
}

// sanitizeName sanitizes a name to lowercase
func (r *Reader) sanitizeName(name string) string {
	return strings.ToLower(name)
}