package ast

import (
	"fmt"
	"strings"

	"gopkg.in/yaml.v3"

	"github.com/go-task/task/v3/internal/experiments"
	"github.com/go-task/task/v3/internal/omap"
)

// Vars is a string[string] variables map.
type Vars struct {
	omap.OrderedMap[string, Var]
}

// ToCacheMap converts Vars to a map containing only the static
// variables
func (vs *Vars) ToCacheMap() (m map[string]any) {
	m = make(map[string]any, vs.Len())
	_ = vs.Range(func(k string, v Var) error {
		if v.Sh != "" {
			// Dynamic variable is not yet resolved; trigger
			// <no value> to be used in templates.
			return nil
		}

		if v.Live != nil {
			m[k] = v.Live
		} else {
			m[k] = v.Value
		}
		return nil
	})
	return
}

// Wrapper around OrderedMap.Set to ensure we don't get nil pointer errors
func (vs *Vars) Range(f func(k string, v Var) error) error {
	if vs == nil {
		return nil
	}
	return vs.OrderedMap.Range(f)
}

// Wrapper around OrderedMap.Merge to ensure we don't get nil pointer errors
func (vs *Vars) Merge(other *Vars) {
	if vs == nil || other == nil {
		return
	}
	vs.OrderedMap.Merge(other.OrderedMap)
}

// Wrapper around OrderedMap.Len to ensure we don't get nil pointer errors
func (vs *Vars) Len() int {
	if vs == nil {
		return 0
	}
	return vs.OrderedMap.Len()
}

// DeepCopy creates a new instance of Vars and copies
// data by value from the source struct.
func (vs *Vars) DeepCopy() *Vars {
	if vs == nil {
		return nil
	}
	return &Vars{
		OrderedMap: vs.OrderedMap.DeepCopy(),
	}
}

// Var represents either a static or dynamic variable.
type Var struct {
	Value any
	Live  any
	Sh    string
	Dir   string
}

func (v *Var) UnmarshalYAML(node *yaml.Node) error {
	if experiments.AnyVariables.Enabled {
		var value any
		if err := node.Decode(&value); err != nil {
			return err
		}
		// If the value is a string and it starts with $, then it's a shell command
		if str, ok := value.(string); ok {
			if str, ok = strings.CutPrefix(str, "$"); ok {
				v.Sh = str
				return nil
			}
		}
		v.Value = value
		return nil
	}

	switch node.Kind {

	case yaml.ScalarNode:
		var str string
		if err := node.Decode(&str); err != nil {
			return err
		}
		v.Value = str
		return nil

	case yaml.MappingNode:
		var sh struct {
			Sh string
		}
		if err := node.Decode(&sh); err != nil {
			return err
		}
		v.Sh = sh.Sh
		return nil
	}

	return fmt.Errorf("yaml: line %d: cannot unmarshal %s into variable", node.Line, node.ShortTag())
}