package convert

import (
	"context"

	"github.com/hashicorp/go-cty/cty"

	"github.com/hashicorp/terraform-plugin-go/tfprotov5"
	"github.com/hashicorp/terraform-plugin-go/tftypes"
	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
	"github.com/hashicorp/terraform-plugin-sdk/v2/internal/logging"
)

// AppendProtoDiag appends a new diagnostic from a warning string or an error.
// This panics if d is not a string or error.
func AppendProtoDiag(ctx context.Context, diags []*tfprotov5.Diagnostic, d interface{}) []*tfprotov5.Diagnostic {
	switch d := d.(type) {
	case cty.PathError:
		ap := PathToAttributePath(d.Path)
		diagnostic := &tfprotov5.Diagnostic{
			Severity:  tfprotov5.DiagnosticSeverityError,
			Summary:   d.Error(),
			Attribute: ap,
		}

		if diagnostic.Summary == "" {
			logging.HelperSchemaWarn(ctx, "detected empty error string for diagnostic in AppendProtoDiag for cty.PathError type")
			diagnostic.Summary = "Empty Error String"
			diagnostic.Detail = "This is always a bug in the provider and should be reported to the provider developers."
		}

		diags = append(diags, diagnostic)
	case diag.Diagnostics:
		diags = append(diags, DiagsToProto(d)...)
	case error:
		if d == nil {
			logging.HelperSchemaDebug(ctx, "skipping diagnostic for nil error in AppendProtoDiag")
			return diags
		}

		diagnostic := &tfprotov5.Diagnostic{
			Severity: tfprotov5.DiagnosticSeverityError,
			Summary:  d.Error(),
		}

		if diagnostic.Summary == "" {
			logging.HelperSchemaWarn(ctx, "detected empty error string for diagnostic in AppendProtoDiag for error type")
			diagnostic.Summary = "Error Missing Message"
			diagnostic.Detail = "This is always a bug in the provider and should be reported to the provider developers."
		}

		diags = append(diags, diagnostic)
	case string:
		if d == "" {
			logging.HelperSchemaDebug(ctx, "skipping diagnostic for empty string in AppendProtoDiag")
			return diags
		}

		diags = append(diags, &tfprotov5.Diagnostic{
			Severity: tfprotov5.DiagnosticSeverityWarning,
			Summary:  d,
		})
	case *tfprotov5.Diagnostic:
		diags = append(diags, d)
	case []*tfprotov5.Diagnostic:
		diags = append(diags, d...)
	}
	return diags
}

// ProtoToDiags converts a list of tfprotov5.Diagnostics to a diag.Diagnostics.
func ProtoToDiags(ds []*tfprotov5.Diagnostic) diag.Diagnostics {
	var diags diag.Diagnostics
	for _, d := range ds {
		var severity diag.Severity

		switch d.Severity {
		case tfprotov5.DiagnosticSeverityError:
			severity = diag.Error
		case tfprotov5.DiagnosticSeverityWarning:
			severity = diag.Warning
		}

		diags = append(diags, diag.Diagnostic{
			Severity:      severity,
			Summary:       d.Summary,
			Detail:        d.Detail,
			AttributePath: AttributePathToPath(d.Attribute),
		})
	}

	return diags
}

func DiagsToProto(diags diag.Diagnostics) []*tfprotov5.Diagnostic {
	var ds []*tfprotov5.Diagnostic
	for _, d := range diags {
		protoDiag := &tfprotov5.Diagnostic{
			Severity:  tfprotov5.DiagnosticSeverityError,
			Summary:   d.Summary,
			Detail:    d.Detail,
			Attribute: PathToAttributePath(d.AttributePath),
		}
		if d.Severity == diag.Warning {
			protoDiag.Severity = tfprotov5.DiagnosticSeverityWarning
		}
		if d.Summary == "" {
			protoDiag.Summary = "Empty Summary: This is always a bug in the provider and should be reported to the provider developers."
		}
		ds = append(ds, protoDiag)
	}
	return ds
}

// AttributePathToPath takes the proto encoded path and converts it to a cty.Path
func AttributePathToPath(ap *tftypes.AttributePath) cty.Path {
	var p cty.Path
	if ap == nil {
		return p
	}
	for _, step := range ap.Steps() {
		switch step := step.(type) {
		case tftypes.AttributeName:
			p = p.GetAttr(string(step))
		case tftypes.ElementKeyString:
			p = p.Index(cty.StringVal(string(step)))
		case tftypes.ElementKeyInt:
			p = p.Index(cty.NumberIntVal(int64(step)))
		}
	}
	return p
}

// PathToAttributePath takes a cty.Path and converts it to a proto-encoded path.
func PathToAttributePath(p cty.Path) *tftypes.AttributePath {
	if p == nil || len(p) < 1 {
		return nil
	}
	ap := tftypes.NewAttributePath()
	for _, step := range p {
		switch selector := step.(type) {
		case cty.GetAttrStep:
			ap = ap.WithAttributeName(selector.Name)

		case cty.IndexStep:
			key := selector.Key
			switch key.Type() {
			case cty.String:
				ap = ap.WithElementKeyString(key.AsString())
			case cty.Number:
				v, _ := key.AsBigFloat().Int64()
				ap = ap.WithElementKeyInt(int(v))
			default:
				// We'll bail early if we encounter anything else, and just
				// return the valid prefix.
				return ap
			}
		}
	}
	return ap
}