// Copyright © 2022 Roberto Hidalgo <chinampa@un.rob.mx>
// SPDX-License-Identifier: Apache-2.0
package command

import (
	"fmt"
	"strings"

	"git.rob.mx/nidito/chinampa/pkg/errors"
	"github.com/spf13/cobra"
)

func contains(haystack []string, needle string) bool {
	for _, validValue := range haystack {
		if needle == validValue {
			return true
		}
	}
	return false
}

// Arguments is an ordered list of Argument.
type Arguments []*Argument

func (args *Arguments) AllKnown() map[string]any {
	col := map[string]any{}
	for _, arg := range *args {
		col[arg.Name] = arg.ToValue()
	}
	return col
}

func (args *Arguments) AllKnownStr() map[string]string {
	col := map[string]string{}
	for _, arg := range *args {
		col[arg.Name] = arg.ToString()
	}
	return col
}

func anySliceToStringSlice(src any) []string {
	res := []string{}
	switch d := src.(type) {
	case []string:
		res = d
	case []any:
		for _, valI := range d {
			res = append(res, valI.(string))
		}
	}
	return res
}

func (args *Arguments) Parse(supplied []string) error {
	parsed := []string{}
	for idx, arg := range *args {
		argumentProvided := idx < len(supplied)

		if !argumentProvided {
			if arg.Default != nil {
				if arg.Variadic {
					defaultSlice := anySliceToStringSlice(arg.Default)
					arg.provided = &defaultSlice
				} else {
					defaultString := arg.Default.(string)
					if defaultString != "" {
						arg.provided = &[]string{defaultString}
					}
				}
			}
			continue
		}

		if arg.Variadic {
			values := append([]string{}, supplied[idx:]...)
			arg.SetValue(values)
		} else {
			arg.SetValue([]string{supplied[idx]})
		}
		parsed = append(parsed, *arg.provided...)
	}

	if len(parsed) != len(supplied) {
		return errors.BadArguments{Msg: fmt.Sprintf("Unexpected arguments provided: %s", supplied)}
	}
	return nil
}

func (args *Arguments) AreValid() error {
	for _, arg := range *args {
		if err := arg.Validate(); err != nil {
			return err
		}
	}

	return nil
}

// CompletionFunction is called by cobra when asked to complete arguments.
func (args *Arguments) CompletionFunction(cc *cobra.Command, provided []string, toComplete string) ([]string, cobra.ShellCompDirective) {
	expectedArgLen := len(*args)
	values := []string{}
	directive := cobra.ShellCompDirectiveError

	if cc.HasAvailableSubCommands() && len(provided) < 1 {
		// if this is an "index" command and user is providing first argument
		// allow completions instead of erroring by default
		directive = cobra.ShellCompDirectiveDefault
	}

	if expectedArgLen > 0 {
		argsCompleted := len(provided)
		lastArg := (*args)[len(*args)-1]
		hasVariadicArg := expectedArgLen > 0 && lastArg.Variadic
		lastArg.Command.Options.Parse(cc.Flags())
		if err := args.Parse(provided); err != nil {
			return []string{err.Error()}, cobra.ShellCompDirectiveDefault
		}

		directive = cobra.ShellCompDirectiveDefault
		if argsCompleted < expectedArgLen || hasVariadicArg {
			var arg *Argument
			if hasVariadicArg && argsCompleted >= expectedArgLen {
				// completing a variadic argument
				arg = lastArg
			} else {
				// completing regular argument (maybe variadic!)
				arg = (*args)[argsCompleted]
			}

			if arg.Values != nil {
				var err error
				arg.Values.command = lastArg.Command
				arg.Command = lastArg.Command
				values, directive, err = arg.Resolve(toComplete)
				if err != nil {
					return []string{err.Error()}, cobra.ShellCompDirectiveDefault
				}
			} else {
				directive = cobra.ShellCompDirectiveError
			}
			values = cobra.AppendActiveHelp(values, arg.Description)
		}

		if toComplete != "" && directive != cobra.ShellCompDirectiveFilterFileExt && directive != cobra.ShellCompDirectiveFilterDirs {
			filtered := []string{}
			for _, value := range values {
				if strings.HasPrefix(value, toComplete) {
					filtered = append(filtered, value)
				}
			}
			values = filtered
		}
	}

	return values, directive
}

// Argument represents a single command-line argument.
type Argument struct {
	// Name is how this variable will be exposed to the underlying command.
	Name string `json:"name" yaml:"name" validate:"required,excludesall=!$\\/%^@#?:'\""`
	// Description is what this argument is for.
	Description string `json:"description" yaml:"description" validate:"required"`
	// Default is the default value for this argument if none is provided.
	Default any `json:"default,omitempty" yaml:"default,omitempty" validate:"excluded_with=Required"`
	// Variadic makes an argument a list of all values from this one on.
	Variadic bool `json:"variadic" yaml:"variadic"`
	// Required raises an error if an argument is not provided.
	Required bool `json:"required" yaml:"required" validate:"excluded_with=Default"`
	// Values describes autocompletion and validation for an argument
	Values   *ValueSource `json:"values,omitempty" yaml:"values" validate:"omitempty"`
	Command  *Command     `json:"-" yaml:"-" validate:"-"`
	provided *[]string
}

func (arg *Argument) EnvName() string {
	return strings.ToUpper(strings.ReplaceAll(arg.Name, "-", "_"))
}

func (arg *Argument) SetValue(value []string) {
	arg.provided = &value
}

func (arg *Argument) IsKnown() bool {
	return arg.provided != nil && len(*arg.provided) > 0
}

func (arg *Argument) ToString() string {
	val := arg.ToValue()

	if arg.Variadic {
		val := val.([]string)
		return strings.Join(val, " ")
	}

	return val.(string)
}

func (arg *Argument) ToValue() any {
	var value any
	if arg.IsKnown() {
		if arg.Variadic {
			value = *arg.provided
		} else {
			vals := *arg.provided
			value = vals[0]
		}
	} else {
		if arg.Default != nil {
			if arg.Variadic {
				defaultSlice := anySliceToStringSlice(arg.Default)
				// for _, valI := range arg.Default.([]any) {
				// 	valStr := valI.(string)
				// 	defaultSlice = append(defaultSlice, valStr)
				// }

				value = defaultSlice
			} else {
				value = arg.Default.(string)
			}
		} else {
			if arg.Variadic {
				value = []string{}
			} else {
				value = ""
			}
		}
	}

	return value
}

func (arg *Argument) Validate() error {
	if !arg.IsKnown() {
		if arg.Required {
			return errors.BadArguments{Msg: fmt.Sprintf("Missing argument for %s", strings.ToUpper(arg.Name))}
		}

		return nil
	}

	if !arg.Validates() {
		return nil
	}

	validValues, _, err := arg.Resolve(strings.Join(*arg.provided, " "))
	if err != nil {
		return err
	}

	if arg.Variadic {
		for _, current := range *arg.provided {
			if !contains(validValues, current) {
				return errors.BadArguments{Msg: fmt.Sprintf("%s is not a valid value for argument <%s>. Valid options are: %s", current, arg.Name, strings.Join(validValues, ", "))}
			}
		}
	} else {
		current := arg.ToValue().(string)
		if !contains(validValues, current) {
			return errors.BadArguments{Msg: fmt.Sprintf("%s is not a valid value for argument <%s>. Valid options are: %s", current, arg.Name, strings.Join(validValues, ", "))}
		}
	}

	return nil
}

// Validates tells if the user-supplied value needs validation.
func (arg *Argument) Validates() bool {
	return arg.Values != nil && arg.Values.Validates()
}

// ToDesc prints out the description of an argument for help and docs.
func (arg *Argument) ToDesc() string {
	spec := arg.EnvName()
	if arg.Variadic {
		spec = fmt.Sprintf("%s...", spec)
	}

	if !arg.Required {
		spec = fmt.Sprintf("[%s]", spec)
	}

	return spec
}

// Resolve returns autocomplete values for an argument.
func (arg *Argument) Resolve(current string) (values []string, flag cobra.ShellCompDirective, err error) {
	if arg.Values != nil {
		values, flag, err = arg.Values.Resolve(current)
		if err != nil {
			flag = cobra.ShellCompDirectiveError
			return
		}
	}

	return
}