// Copyright (c) The OpenTofu Authors
// SPDX-License-Identifier: MPL-2.0
// Copyright (c) 2023 HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0

package configs

import (
	"context"
	"fmt"

	"github.com/hashicorp/hcl/v2"
	"github.com/hashicorp/hcl/v2/gohcl"
	"github.com/hashicorp/hcl/v2/hcldec"
	"github.com/opentofu/opentofu/internal/addrs"
	"github.com/opentofu/opentofu/internal/lang"
	"github.com/opentofu/opentofu/internal/lang/marks"
	"github.com/zclconf/go-cty/cty"
)

// StaticIdentifier holds a Referenceable item and where it was declared
type StaticIdentifier struct {
	Module    addrs.Module
	Subject   string
	DeclRange hcl.Range
}

func (ref StaticIdentifier) String() string {
	val := ref.Subject
	if len(ref.Module) != 0 {
		val = ref.Module.String() + ":" + val
	}
	return val
}

type StaticModuleVariables func(v *Variable) (cty.Value, hcl.Diagnostics)

// StaticModuleCall contains the information required to call a given module
type StaticModuleCall struct {
	addr      addrs.Module
	vars      StaticModuleVariables
	rootPath  string
	workspace string
}

func NewStaticModuleCall(addr addrs.Module, vars StaticModuleVariables, rootPath string, workspace string) StaticModuleCall {
	return StaticModuleCall{
		addr:      addr,
		vars:      vars,
		rootPath:  rootPath,
		workspace: workspace,
	}
}

func (s StaticModuleCall) Variables() StaticModuleVariables {
	return s.vars
}

func (s StaticModuleCall) WithVariables(vars StaticModuleVariables) StaticModuleCall {
	return StaticModuleCall{
		addr:      s.addr,
		vars:      vars,
		rootPath:  s.rootPath,
		workspace: s.workspace,
	}
}

// only used in testing
func RootModuleCallForTesting() StaticModuleCall {
	return NewStaticModuleCall(addrs.RootModule, func(_ *Variable) (cty.Value, hcl.Diagnostics) {
		panic("Variables have not been configured for this test!")
	}, "<testing>", "")
}

// A static evaluator contains the information required to build a EvalContext
// which only understands "static" (non-state) data. Internally, it relies
// on staticData
type StaticEvaluator struct {
	call StaticModuleCall
	cfg  *Module
}

// Creates a static evaluator based from the given module and module call
func NewStaticEvaluator(mod *Module, call StaticModuleCall) *StaticEvaluator {
	return &StaticEvaluator{
		call: call,
		cfg:  mod,
	}
}

func (s *StaticEvaluator) scope(ident StaticIdentifier) *lang.Scope {
	return newStaticScope(s, ident)
}

func (s StaticEvaluator) Evaluate(ctx context.Context, expr hcl.Expression, ident StaticIdentifier) (cty.Value, hcl.Diagnostics) {
	val, diags := s.scope(ident).EvalExpr(ctx, expr, cty.DynamicPseudoType)
	return val, diags.ToHCL()
}

func (s StaticEvaluator) DecodeExpression(ctx context.Context, expr hcl.Expression, ident StaticIdentifier, val any) hcl.Diagnostics {
	srcVal, diags := s.Evaluate(ctx, expr, ident)
	if diags.HasErrors() {
		return diags
	}

	if marks.Contains(srcVal, marks.Sensitive) {
		return diags.Append(&hcl.Diagnostic{
			Severity: hcl.DiagError,
			Summary:  "Sensitive value not allowed",
			Detail:   fmt.Sprintf("Sensitive values, or values derived from sensitive values, cannot be used as %s.", ident.String()),
			Subject:  expr.Range().Ptr(),
		})
	}
	if marks.Contains(srcVal, marks.Ephemeral) {
		return diags.Append(&hcl.Diagnostic{
			Severity: hcl.DiagError,
			Summary:  "Ephemeral value not allowed",
			Detail:   fmt.Sprintf("Ephemeral values, or values derived from ephemeral values, cannot be used as %s.", ident.String()),
			Subject:  expr.Range().Ptr(),
		})
	}

	return diags.Extend(gohcl.DecodeValue(srcVal, expr.StartRange(), expr.Range(), val))
}

func (s StaticEvaluator) DecodeBlock(ctx context.Context, body hcl.Body, spec hcldec.Spec, ident StaticIdentifier) (cty.Value, hcl.Diagnostics) {
	var diags hcl.Diagnostics

	refs, refsDiags := lang.References(addrs.ParseRef, hcldec.Variables(body, spec))
	diags = append(diags, refsDiags.ToHCL()...)
	if diags.HasErrors() {
		return cty.DynamicVal, diags
	}

	hclCtx, ctxDiags := s.scope(ident).EvalContext(ctx, refs)
	diags = append(diags, ctxDiags.ToHCL()...)
	if diags.HasErrors() {
		return cty.DynamicVal, diags
	}

	val, valDiags := hcldec.Decode(body, spec, hclCtx)
	diags = append(diags, valDiags...)
	return val, diags
}

func (s StaticEvaluator) EvalContext(ctx context.Context, ident StaticIdentifier, refs []*addrs.Reference) (*hcl.EvalContext, hcl.Diagnostics) {
	return s.EvalContextWithParent(ctx, nil, ident, refs)
}

func (s StaticEvaluator) EvalContextWithParent(ctx context.Context, parent *hcl.EvalContext, ident StaticIdentifier, refs []*addrs.Reference) (*hcl.EvalContext, hcl.Diagnostics) {
	evalCtx, diags := s.scope(ident).EvalContextWithParent(ctx, parent, refs)
	return evalCtx, diags.ToHCL()
}
