package artifacts

import (
	"fmt"
	"sort"
	"strings"

	"gitea.maximumdirect.net/eric/narratio/internal/config"
)

// PreviousArtifactRequirement describes one previous-session artifact dependency.
type PreviousArtifactRequirement struct {
	Name     string
	Required bool
	Sources  []string
}

// CollectPreviousArtifactRequirements scans enabled Scriptorium artifacts and returns
// deduplicated previous-session artifact requirements in deterministic order.
func CollectPreviousArtifactRequirements(
	artifactsCfg map[string]config.ScriptoriumArtifactConfig,
) []PreviousArtifactRequirement {
	if len(artifactsCfg) == 0 {
		return nil
	}

	artifactNames := sortedScriptoriumArtifactNames(artifactsCfg)
	byName := map[string]PreviousArtifactRequirement{}

	for _, artifactName := range artifactNames {
		artifactCfg := artifactsCfg[artifactName]
		if !artifactCfg.Enabled {
			continue
		}

		inputNames := sortedScriptoriumInputKeys(artifactCfg.Inputs)
		for _, inputName := range inputNames {
			inputCfg := artifactCfg.Inputs[inputName]
			previousName, ok := PreviousSessionArtifactName(inputCfg.Source)
			if !ok {
				continue
			}

			location := fmt.Sprintf(
				"pipeline.scriptorium.artifacts.%s.inputs.%s.source",
				artifactName,
				inputName,
			)
			requirement := byName[previousName]
			requirement.Name = previousName
			requirement.Required = requirement.Required || inputCfg.Required
			requirement.Sources = append(requirement.Sources, location)
			byName[previousName] = requirement
		}
	}

	if len(byName) == 0 {
		return nil
	}

	requirements := make([]PreviousArtifactRequirement, 0, len(byName))
	for _, requirement := range byName {
		requirement.Sources = dedupeAndSortStrings(requirement.Sources)
		requirements = append(requirements, requirement)
	}
	sort.Slice(requirements, func(i, j int) bool {
		return requirements[i].Name < requirements[j].Name
	})
	return requirements
}

func sortedScriptoriumArtifactNames(artifactsCfg map[string]config.ScriptoriumArtifactConfig) []string {
	names := make([]string, 0, len(artifactsCfg))
	for name := range artifactsCfg {
		names = append(names, name)
	}
	sort.Strings(names)
	return names
}

func sortedScriptoriumInputKeys(inputs map[string]config.ScriptoriumInputConfig) []string {
	if len(inputs) == 0 {
		return nil
	}
	names := make([]string, 0, len(inputs))
	for name := range inputs {
		names = append(names, name)
	}
	sort.Strings(names)
	return names
}

func dedupeAndSortStrings(values []string) []string {
	if len(values) == 0 {
		return nil
	}
	seen := map[string]struct{}{}
	out := make([]string, 0, len(values))
	for _, value := range values {
		trimmed := strings.TrimSpace(value)
		if trimmed == "" {
			continue
		}
		if _, ok := seen[trimmed]; ok {
			continue
		}
		seen[trimmed] = struct{}{}
		out = append(out, trimmed)
	}
	sort.Strings(out)
	return out
}