// Package promptinput builds prompt data packages from briefing packages.
package promptinput

import (
	"fmt"
	"time"

	"gitea.maximumdirect.net/eric/weatherreporter/internal/briefing"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/changes"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/fileutil"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/report"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/timeutil"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/weatherdata"
)

const SchemaVersion = "weatherreporter.data_package.v1"

type Package struct {
	SchemaVersion  string                      `json:"schemaVersion"`
	RunID          string                      `json:"runId"`
	Report         Report                      `json:"report"`
	Briefing       briefing.Package            `json:"briefing"`
	RecentChanges  RecentChanges               `json:"recentChanges"`
	SourceWarnings []weatherdata.SourceWarning `json:"sourceWarnings,omitempty"`
}

type Report struct {
	ID               report.ID       `json:"id"`
	Variant          string          `json:"variant,omitempty"`
	PromptID         string          `json:"promptId"`
	GeneratedAt      time.Time       `json:"generatedAt"`
	Timezone         string          `json:"timezone"`
	CurrentLocalDate string          `json:"currentLocalDate"`
	ValidPeriod      timeutil.Period `json:"validPeriod"`
}

type RecentChanges struct {
	Items []changes.Change `json:"items"`
}

func Build(briefingPackage briefing.Package) (Package, error) {
	return BuildWithRecentChanges(briefingPackage, nil)
}

func BuildWithRecentChanges(briefingPackage briefing.Package, recentChanges []changes.Change) (Package, error) {
	localDate, err := currentLocalDate(briefingPackage.Metadata.GeneratedAt, briefingPackage.Metadata.Timezone)
	if err != nil {
		return Package{}, err
	}
	items := make([]changes.Change, len(recentChanges))
	copy(items, recentChanges)
	if items == nil {
		items = []changes.Change{}
	}
	pkg := Package{
		SchemaVersion: SchemaVersion,
		RunID:         briefingPackage.Metadata.RunID,
		Report: Report{
			ID:               briefingPackage.Metadata.ReportID,
			Variant:          briefingPackage.Metadata.Variant,
			PromptID:         briefingPackage.Metadata.PromptID,
			GeneratedAt:      briefingPackage.Metadata.GeneratedAt,
			Timezone:         briefingPackage.Metadata.Timezone,
			CurrentLocalDate: localDate,
			ValidPeriod:      briefingPackage.Metadata.ValidPeriod,
		},
		Briefing:       briefingPackage,
		RecentChanges:  RecentChanges{Items: items},
		SourceWarnings: briefingPackage.Metadata.SourceWarnings,
	}
	if err := Validate(pkg); err != nil {
		return Package{}, err
	}
	return pkg, nil
}

func currentLocalDate(generatedAt time.Time, timezone string) (string, error) {
	location, err := timeutil.LoadLocation(timezone)
	if err != nil {
		return "", fmt.Errorf("load report timezone %q: %w", timezone, err)
	}
	return generatedAt.In(location).Format(timeutil.DateLayout), nil
}

func Validate(pkg Package) error {
	if pkg.SchemaVersion == "" {
		return fmt.Errorf("schemaVersion is required")
	}
	if pkg.RunID == "" {
		return fmt.Errorf("runId is required")
	}
	if pkg.Report.ID == "" {
		return fmt.Errorf("report.id is required")
	}
	if pkg.Report.PromptID == "" {
		return fmt.Errorf("report.promptId is required")
	}
	if pkg.Report.GeneratedAt.IsZero() {
		return fmt.Errorf("report.generatedAt is required")
	}
	if pkg.Report.Timezone == "" {
		return fmt.Errorf("report.timezone is required")
	}
	if pkg.Report.CurrentLocalDate == "" {
		return fmt.Errorf("report.currentLocalDate is required")
	}
	if !pkg.Report.ValidPeriod.IsValid() {
		return fmt.Errorf("report.validPeriod must be valid")
	}
	if pkg.Briefing.Metadata.RunID == "" {
		return fmt.Errorf("briefing.metadata.runId is required")
	}
	if pkg.Briefing.Metadata.RunID != pkg.RunID {
		return fmt.Errorf("briefing.metadata.runId must match runId")
	}
	if pkg.Briefing.Metadata.SchemaVersion == "" {
		return fmt.Errorf("briefing.metadata.schemaVersion is required")
	}
	if pkg.Briefing.Metadata.PromptID != pkg.Report.PromptID {
		return fmt.Errorf("briefing.metadata.promptId must match report.promptId")
	}
	if pkg.Briefing.Metadata.ReportID != pkg.Report.ID {
		return fmt.Errorf("briefing.metadata.reportId must match report.id")
	}
	if pkg.Briefing.Daily == nil && pkg.Briefing.ThreeDay == nil && pkg.Briefing.Weekend == nil && pkg.Briefing.Storm == nil {
		return fmt.Errorf("briefing report content is required")
	}
	return nil
}

func Save(path string, pkg Package) error {
	if err := Validate(pkg); err != nil {
		return err
	}
	if err := fileutil.WriteJSONAtomic(path, pkg); err != nil {
		return fmt.Errorf("save data package: %w", err)
	}
	return nil
}