package app

import (
	"context"
	"fmt"
	"log/slog"
	"os"

	"gitea.maximumdirect.net/eric/narratio/internal/artifacts"
	"gitea.maximumdirect.net/eric/narratio/internal/config"
	"gitea.maximumdirect.net/eric/narratio/internal/fileops"
	"gitea.maximumdirect.net/eric/narratio/internal/logging"
	"gitea.maximumdirect.net/eric/narratio/internal/manifest"
	"gitea.maximumdirect.net/eric/narratio/internal/stage"
)

type invocationRuntime struct {
	ctx                context.Context
	cfg                *config.Config
	plan               BoundedPlan
	stages             []stage.Stage
	opts               RunOptions
	effectiveArtifacts artifacts.EffectiveArtifactSet
	identity           invocationIdentity
	paths              artifacts.SessionPaths
	env                *stage.Env
	manifestStore      manifest.Store
	artifactStore      artifacts.Store
	manifestPath       string
	manifest           *manifest.Manifest
	stageNames         []string
	executed           []string
	skipped            []string
	dependencies       invocationDependencies
}

func prepareInvocation(ctx context.Context, cfg *config.Config, plan BoundedPlan, opts RunOptions, dependencies invocationDependencies) (*invocationRuntime, error) {
	var prerequisiteStore manifest.Store
	if opts.Env != nil {
		prerequisiteStore = opts.Env.ManifestStore
	}
	if err := inspectBoundedPrerequisites(ctx, cfg, plan, prerequisiteStore); err != nil {
		return nil, fmt.Errorf("validate bounded run prerequisites: %w", err)
	}

	effectiveArtifacts := opts.EffectiveArtifacts
	if !effectiveArtifacts.Resolved() && cfg != nil && cfg.Pipeline != nil && cfg.Pipeline.Scriptorium != nil {
		var err error
		effectiveArtifacts, err = resolveEffectiveArtifacts(cfg, nil)
		if err != nil {
			return nil, fmt.Errorf("resolve effective artifacts: %w", err)
		}
	}
	if !effectiveArtifacts.Resolved() {
		var err error
		effectiveArtifacts, err = artifacts.ResolveEffectiveArtifactSet(nil, nil)
		if err != nil {
			return nil, fmt.Errorf("resolve default effective artifacts: %w", err)
		}
	}

	runID, err := dependencies.newRunID()
	if err != nil {
		return nil, fmt.Errorf("generate run id: %w", err)
	}
	identity, err := resolveInvocationIdentity(cfg, runID)
	if err != nil {
		return nil, fmt.Errorf("resolve invocation identity: %w", err)
	}

	env := opts.Env
	if env == nil {
		env = &stage.Env{}
	}
	// The resolved configuration is the invocation's single source of truth.
	// Injected environments supply collaborators, never alternate invocation data.
	env.Config = cfg
	env.SelectedArtifactKeys = append([]string(nil), opts.SelectedArtifacts...)
	env.EffectiveArtifacts = effectiveArtifacts
	if env.ManifestStore == nil {
		env.ManifestStore = &manifest.LocalStore{}
	}
	if env.ArtifactStore == nil {
		env.ArtifactStore = artifacts.NewLocalStore(cfg.Pipeline.Workspace.Root)
	}
	if env.Logger == nil {
		env.Logger = logging.NewLogger(os.Stderr, slog.LevelInfo)
	}

	normalizedOpts := opts
	normalizedOpts.SelectedArtifacts = append([]string(nil), opts.SelectedArtifacts...)
	normalizedOpts.EffectiveArtifacts = effectiveArtifacts
	normalizedOpts.Env = env
	stages := plan.Stages()
	return &invocationRuntime{
		ctx:                ctx,
		cfg:                cfg,
		plan:               plan,
		stages:             stages,
		opts:               normalizedOpts,
		effectiveArtifacts: effectiveArtifacts,
		identity:           identity,
		env:                env,
		manifestStore:      env.ManifestStore,
		artifactStore:      env.ArtifactStore,
		manifestPath: artifacts.SessionManifestPathForCampaign(
			cfg.Pipeline.Workspace.Root,
			identity.Campaign,
			identity.SessionID,
		),
		stageNames:   make([]string, 0, len(stages)),
		executed:     make([]string, 0, len(stages)),
		skipped:      make([]string, 0, len(stages)),
		dependencies: dependencies,
	}, nil
}

func prepareInvocationLayout(runtime *invocationRuntime) error {
	paths, err := runtime.artifactStore.EnsureLayoutFor(runtime.identity.Campaign, runtime.identity.SessionID)
	if err != nil {
		return fmt.Errorf("prepare workdir: %w", err)
	}
	if paths.ManifestPath != runtime.manifestPath {
		return fmt.Errorf("prepared manifest path %q does not match resolved manifest path %q", paths.ManifestPath, runtime.manifestPath)
	}
	runtime.paths = paths
	return nil
}

func initializeLockedInvocation(runtime *invocationRuntime) error {
	if err := requireCompleteRestore(runtime.paths); err != nil {
		return err
	}
	m, present, err := loadManifestAtPathIfPresent(runtime.ctx, runtime.manifestStore, runtime.manifestPath)
	if err != nil {
		return err
	}
	if present {
		if err := runtime.identity.validateSessionManifest(m); err != nil {
			return err
		}
	} else {
		m, err = runtime.manifestStore.Create(runtime.ctx, runtime.identity.SessionID)
		if err != nil {
			return fmt.Errorf("create manifest: %w", err)
		}
	}
	runtime.manifest = m

	// The unlocked inspection avoids creating invocation state for an invalid
	// request. Recheck while holding the session lock in case prior state changed.
	if err := validateBoundedPrerequisites(runtime.plan, m); err != nil {
		return fmt.Errorf("validate bounded run prerequisites under session lock: %w", err)
	}
	runtime.identity.applyToSessionManifest(m)
	applyEffectiveConfigProvenance(m, runtime.cfg)
	if err := runtime.manifestStore.Save(runtime.ctx, runtime.manifestPath, m); err != nil {
		return fmt.Errorf("save manifest identity %q: %w", runtime.manifestPath, err)
	}
	if err := fileops.EnsureWorkspaceDirectory(runtime.identity.LocalWorkDir); err != nil {
		return runtime.persistTerminalFailure(fmt.Errorf("create run directory %q: %w", runtime.identity.LocalWorkDir, err))
	}
	if _, err := loadSecretsFromConfig(runtime.env.Config, runtime.env.Logger); err != nil {
		return runtime.persistTerminalFailure(fmt.Errorf("load secrets from files: %w", err))
	}
	return nil
}

func (runtime *invocationRuntime) persistTerminalFailure(err error) error {
	return persistSessionTerminalFailure(
		runtime.ctx,
		runtime.manifestStore,
		runtime.manifestPath,
		runtime.manifest,
		err,
		runtime.dependencies.now(),
	)
}