package drawdb

import (
	"encoding/json"
	"fmt"
	"os"
	"strconv"
	"strings"

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

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

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

// ReadDatabase reads and parses DrawDB JSON 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 DrawDB reader")
	}

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

	var drawSchema drawdb.DrawDBSchema
	if err := json.Unmarshal(data, &drawSchema); err != nil {
		return nil, fmt.Errorf("failed to parse DrawDB JSON: %w", err)
	}

	return r.convertToDatabase(&drawSchema)
}

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

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

	var drawSchema drawdb.DrawDBSchema
	if err := json.Unmarshal(data, &drawSchema); err != nil {
		return nil, fmt.Errorf("failed to parse DrawDB JSON: %w", err)
	}

	// Determine schema name from the first table, or use "public" as default
	schemaName := "public"
	if len(drawSchema.Tables) > 0 && drawSchema.Tables[0].Schema != "" {
		schemaName = drawSchema.Tables[0].Schema
	}

	return r.convertToSchema(&drawSchema, schemaName)
}

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

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

	var drawSchema drawdb.DrawDBSchema
	if err := json.Unmarshal(data, &drawSchema); err != nil {
		return nil, fmt.Errorf("failed to parse DrawDB JSON: %w", err)
	}

	if len(drawSchema.Tables) == 0 {
		return nil, fmt.Errorf("no tables found in DrawDB JSON")
	}

	// Return the first table
	return r.convertToTable(drawSchema.Tables[0], &drawSchema)
}

// convertToDatabase converts a DrawDB schema to a Database model
func (r *Reader) convertToDatabase(drawSchema *drawdb.DrawDBSchema) (*models.Database, error) {
	db := models.InitDatabase("database")

	if r.options.Metadata != nil {
		if name, ok := r.options.Metadata["name"].(string); ok {
			db.Name = name
		}
	}

	// Extract database info from notes
	for _, note := range drawSchema.Notes {
		if strings.HasPrefix(note.Content, "Database:") {
			parts := strings.SplitN(note.Content, "\n\n", 2)
			if len(parts) == 2 {
				db.Description = parts[1]
			}
		}
	}

	// Group tables by schema
	schemaMap := make(map[string]*models.Schema)

	for _, drawTable := range drawSchema.Tables {
		schemaName := drawTable.Schema
		if schemaName == "" {
			schemaName = "public"
		}

		schema, exists := schemaMap[schemaName]
		if !exists {
			schema = models.InitSchema(schemaName)
			schemaMap[schemaName] = schema
		}

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

		schema.Tables = append(schema.Tables, table)
	}

	// Add schemas to database
	for _, schema := range schemaMap {
		db.Schemas = append(db.Schemas, schema)
	}

	return db, nil
}

// convertToSchema converts DrawDB tables to a Schema model
func (r *Reader) convertToSchema(drawSchema *drawdb.DrawDBSchema, schemaName string) (*models.Schema, error) {
	schema := models.InitSchema(schemaName)

	for _, drawTable := range drawSchema.Tables {
		// Filter by schema if specified in the table
		if drawTable.Schema != "" && drawTable.Schema != schemaName {
			continue
		}

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

		schema.Tables = append(schema.Tables, table)
	}

	return schema, nil
}

// convertToTable converts a DrawDB table to a Table model
func (r *Reader) convertToTable(drawTable *drawdb.DrawDBTable, drawSchema *drawdb.DrawDBSchema) (*models.Table, error) {
	schemaName := drawTable.Schema
	if schemaName == "" {
		schemaName = "public"
	}

	table := models.InitTable(drawTable.Name, schemaName)
	table.Description = drawTable.Comment

	// Convert fields to columns
	for _, field := range drawTable.Fields {
		column := r.convertToColumn(field, drawTable.Name, schemaName)
		table.Columns[column.Name] = column
	}

	// Convert indexes
	for _, index := range drawTable.Indexes {
		idx := r.convertToIndex(index, drawTable, schemaName)
		table.Indexes[idx.Name] = idx
	}

	// Find and convert relationships/constraints for this table
	for _, rel := range drawSchema.Relationships {
		if rel.StartTableID == drawTable.ID {
			constraint := r.convertToConstraint(rel, drawSchema)
			if constraint != nil {
				table.Constraints[constraint.Name] = constraint
			}
		}
	}

	return table, nil
}

// convertToColumn converts a DrawDB field to a Column model
func (r *Reader) convertToColumn(field *drawdb.DrawDBField, tableName, schemaName string) *models.Column {
	column := models.InitColumn(field.Name, tableName, schemaName)

	// Parse type and dimensions
	typeStr := field.Type
	column.Type = typeStr

	// Try to extract length/precision from type string like "varchar(255)" or "decimal(10,2)"
	if strings.Contains(typeStr, "(") {
		parts := strings.Split(typeStr, "(")
		column.Type = parts[0]

		if len(parts) > 1 {
			dimensions := strings.TrimSuffix(parts[1], ")")
			if strings.Contains(dimensions, ",") {
				// Precision and scale (e.g., decimal(10,2))
				dims := strings.Split(dimensions, ",")
				if precision, err := strconv.Atoi(strings.TrimSpace(dims[0])); err == nil {
					column.Precision = precision
				}
				if len(dims) > 1 {
					if scale, err := strconv.Atoi(strings.TrimSpace(dims[1])); err == nil {
						column.Scale = scale
					}
				}
			} else {
				// Just length (e.g., varchar(255))
				if length, err := strconv.Atoi(dimensions); err == nil {
					column.Length = length
				}
			}
		}
	}

	column.IsPrimaryKey = field.Primary
	column.NotNull = field.NotNull || field.Primary
	column.AutoIncrement = field.Increment
	column.Comment = field.Comment

	if field.Default != "" {
		column.Default = field.Default
	}

	return column
}

// convertToIndex converts a DrawDB index to an Index model
func (r *Reader) convertToIndex(drawIndex *drawdb.DrawDBIndex, drawTable *drawdb.DrawDBTable, schemaName string) *models.Index {
	index := models.InitIndex(drawIndex.Name)
	index.Table = drawTable.Name
	index.Schema = schemaName
	index.Unique = drawIndex.Unique

	// Convert field IDs to column names
	for _, fieldID := range drawIndex.Fields {
		if fieldID >= 0 && fieldID < len(drawTable.Fields) {
			index.Columns = append(index.Columns, drawTable.Fields[fieldID].Name)
		}
	}

	return index
}

// convertToConstraint converts a DrawDB relationship to a Constraint model
func (r *Reader) convertToConstraint(rel *drawdb.DrawDBRelationship, drawSchema *drawdb.DrawDBSchema) *models.Constraint {
	// Find the start and end tables
	var startTable, endTable *drawdb.DrawDBTable
	for _, table := range drawSchema.Tables {
		if table.ID == rel.StartTableID {
			startTable = table
		}
		if table.ID == rel.EndTableID {
			endTable = table
		}
	}

	if startTable == nil || endTable == nil {
		return nil
	}

	constraint := models.InitConstraint(rel.Name, models.ForeignKeyConstraint)

	// Get the column names from field IDs
	if rel.StartFieldID >= 0 && rel.StartFieldID < len(startTable.Fields) {
		constraint.Columns = append(constraint.Columns, startTable.Fields[rel.StartFieldID].Name)
	}

	if rel.EndFieldID >= 0 && rel.EndFieldID < len(endTable.Fields) {
		constraint.ReferencedColumns = append(constraint.ReferencedColumns, endTable.Fields[rel.EndFieldID].Name)
	}

	constraint.Table = startTable.Name
	constraint.Schema = startTable.Schema
	if constraint.Schema == "" {
		constraint.Schema = "public"
	}

	constraint.ReferencedTable = endTable.Name
	constraint.ReferencedSchema = endTable.Schema
	if constraint.ReferencedSchema == "" {
		constraint.ReferencedSchema = "public"
	}

	constraint.OnUpdate = rel.UpdateConstraint
	constraint.OnDelete = rel.DeleteConstraint

	return constraint
}