package parser

import (
	"fmt"
	"go/ast"
)

// findBoundStructs will search through the Wails project looking
// for which structs have been bound using the `Bind()` method
func (p *Parser) findBoundStructs(pkg *Package) error {

	// Iterate through the files in the package looking for the bound structs
	for _, fileAst := range pkg.Gopackage.Syntax {

		// Find the wails import name
		wailsImportName := pkg.getWailsImportName(fileAst)

		// If this file doesn't import wails, continue
		if wailsImportName == "" {
			continue
		}

		applicationVariableName := pkg.getApplicationVariableName(fileAst, wailsImportName)
		if applicationVariableName == "" {
			continue
		}

		var parseError error

		ast.Inspect(fileAst, func(n ast.Node) bool {
			// Parse Call expressions looking for bind calls
			callExpr, ok := n.(*ast.CallExpr)
			if !ok {
				return true
			}
			// Check this is the right kind of expression (something.something())
			f, ok := callExpr.Fun.(*ast.SelectorExpr)
			if !ok {
				return true
			}
			ident, ok := f.X.(*ast.Ident)
			if !ok {
				return true
			}

			if ident.Name != applicationVariableName {
				return true
			}

			if f.Sel.Name != "Bind" {
				return true
			}

			if len(callExpr.Args) != 1 {
				return true
			}

			// Work out what was bound
			switch boundItem := callExpr.Args[0].(type) {

			// app.Bind( someFunction() )
			case *ast.CallExpr:
				switch fn := boundItem.Fun.(type) {
				case *ast.Ident:
					// boundStructs = append(boundStructs, newStruct(pkg.Name, fn.Name))
					strct, err := p.getFunctionReturnType(pkg, fn.Name)
					if err != nil {
						parseError = err
						return false
					}
					if strct == nil {
						parseError = fmt.Errorf("unable to resolve function returntype: %s", fn.Name)
						return false
					}
					strct.Package.boundStructs.Add(strct.Name)
				case *ast.SelectorExpr:
					ident, ok := fn.X.(*ast.Ident)
					if !ok {
						return true
					}
					packageName := ident.Name
					functionName := fn.Sel.Name
					println("Found bound function:", packageName+"."+functionName)

					// Get package for package name
					externalPackageName := pkg.getImportByName(packageName, fileAst)
					externalPackage := p.getPackageByID(externalPackageName.ID)

					strct, err := p.getFunctionReturnType(externalPackage, functionName)
					if err != nil {
						parseError = err
						return false
					}
					if strct == nil {
						// Unable to resolve function
						return true
					}
					externalPackage.boundStructs.Add(strct.Name)
				}

			// Binding struct pointer literals
			case *ast.UnaryExpr:

				if boundItem.Op.String() != "&" {
					return true
				}

				cl, ok := boundItem.X.(*ast.CompositeLit)
				if !ok {
					return true
				}

				switch boundStructExp := cl.Type.(type) {

				// app.Bind( &myStruct{} )
				case *ast.Ident:
					pkg.boundStructs.Add(boundStructExp.Name)

				// app.Bind( &mypackage.myStruct{} )
				case *ast.SelectorExpr:
					var structName = ""
					var packageName = ""
					switch x := boundStructExp.X.(type) {
					case *ast.Ident:
						packageName = x.Name
					default:
						// TODO: Save these warnings
						// println("Identifier in binding not supported:")
						return true
					}
					structName = boundStructExp.Sel.Name
					referencedPackage := pkg.getImportByName(packageName, fileAst)
					packageWrapper := p.getPackageByID(referencedPackage.ID)
					packageWrapper.boundStructs.Add(structName)
				}

			default:
				// TODO: Save these warnings
				// println("Unsupported bind expression:")
				// spew.Dump(boundItem)
			}

			return true
		})

		if parseError != nil {
			return parseError
		}
	}

	return nil
}