package build

import (
	"context"
	"fmt"
	"strings"

	"git.novox.be/novox/mesh-delivery/contracts/go/seats/meshbuilds"
	"git.novox.be/novox/mesh-delivery/contracts/go/seats/meshcatalog"
	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-builder/builds"
)

// **A candidate's build is the runner's step ask** (design 47 G A-97, A-84, A-99): the runner's asking half asks the seat
// mesh-builds a `build` step naming each entry by fingerprint, and the builder, its one entry point for a candidate, reads each
// entry through the seat mesh-catalog's `entry` (the repository and the commit are the member's head), builds it as it builds any
// fingerprint (the existing claim, plan and lanes) and answers the step's end. A build is per fingerprint, so no pull request
// number is needed, and the builder follows no candidate.

// BuildStep builds the entries of one step ask and answers its end: passed when every entry's build is done, failed when one
// failed (said), could not run when an entry could not be read, nothing to run for an ask naming none. The ask's id and the node
// are the caller's to set.
func (b *Builder) BuildStep(ctx context.Context, run meshbuilds.StepRun) meshbuilds.StepEnded {
	b.init()
	started := b.now()
	end := meshbuilds.StepEnded{V: 1, Pipeline: run.Pipeline, Step: meshbuilds.StepEndedStepBuild, Rerun: run.Rerun, By: run.By, Entries: run.Entries, Node: b.Node, Started: &started}
	finish := func(outcome, said string) meshbuilds.StepEnded {
		at := b.now()
		end.Ended, end.Outcome, end.Said = &at, outcome, said
		return end
	}
	if len(run.Entries) == 0 {
		return finish(meshbuilds.StepEndedOutcomeNothingToRun, "the ask names no entry")
	}
	if b.StepEntry == nil {
		return finish(meshbuilds.StepEndedOutcomeCouldNotRun, "the builder reads no entry of the seat mesh-catalog")
	}
	var failed []string
	for _, e := range run.Entries {
		outcome, said := b.buildEntry(ctx, e)
		switch outcome {
		case meshbuilds.StepEndedOutcomeCouldNotRun:
			return finish(outcome, said)
		case meshbuilds.StepEndedOutcomeFailed:
			failed = append(failed, said)
		}
	}
	if len(failed) > 0 {
		return finish(meshbuilds.StepEndedOutcomeFailed, strings.Join(failed, "; "))
	}
	return finish(meshbuilds.StepEndedOutcomePassed, "")
}

// buildEntry builds one entry at its fingerprint and waits for its end.
func (b *Builder) buildEntry(ctx context.Context, e meshbuilds.BuildEntry) (outcome, said string) {
	entry, err := b.StepEntry(ctx, e.Fingerprint)
	if err != nil {
		return meshbuilds.StepEndedOutcomeCouldNotRun, fmt.Sprintf("the entry %s at %s cannot be read: %v", e.Module, e.Fingerprint, err)
	}
	if entry.Module != e.Module || (e.Commit != "" && entry.Commit != e.Commit) {
		return meshbuilds.StepEndedOutcomeCouldNotRun, fmt.Sprintf("the entry of %s at %s is of %s at %s", e.Module, e.Fingerprint, entry.Module, entry.Commit)
	}
	key, err := builds.BuilderBuildKey(entry.Module, entry.Fp)
	if err != nil {
		return meshbuilds.StepEndedOutcomeCouldNotRun, err.Error()
	}
	ended := b.awaitEnd(key)
	defer b.dropEnd(key, ended)
	if done, failedWords, found := b.keyEnd(ctx, key); found {
		if done {
			return meshbuilds.StepEndedOutcomePassed, ""
		}
		return meshbuilds.StepEndedOutcomeFailed, failedWords
	}
	m := meshcatalog.ModulesByModuleValue{Repository: entry.Repository, Commit: entry.Commit, Fp2: entry.Fp, Manifest: entry.ManifestDigest, Path: entry.Path,
		Toolchains: CatalogToolchains(b.agreedFor(ctx, entry.ManifestDigest)), Packages: entry.Packages}
	b.consider(ctx, entry.Module, m)
	select {
	case log := <-ended:
		if log.Outcome == builds.BuildDone {
			return meshbuilds.StepEndedOutcomePassed, ""
		}
		return meshbuilds.StepEndedOutcomeFailed, fmt.Sprintf("%s at %s: %s %s", log.Module, log.FP, log.Outcome, log.Error)
	case <-ctx.Done():
		return meshbuilds.StepEndedOutcomeCouldNotRun, fmt.Sprintf("%s at %s: the builder stopped before its build ended", entry.Module, entry.Fp)
	}
}

// keyEnd reads the build key: whether it is done, and its error when it failed for good; found only for a key that has ended.
func (b *Builder) keyEnd(ctx context.Context, key string) (done bool, failed string, found bool) {
	raw, _, ok, err := b.Claimer.Store.Get(ctx, key)
	if err != nil || !ok {
		return false, "", false
	}
	v, err := builds.DecodeBuilderBuild(raw)
	if err != nil {
		return false, "", false
	}
	switch {
	case v.State == builds.BuildDone && !Unpublished(v, b.Seats):
		return true, "", true
	case v.State == builds.BuildFailed && builds.FailedUntilChanged(v.Error):
		return false, key + ": " + v.Error, true
	}
	return false, "", false
}

// awaitEnd registers a wait for the end of the build of key, heard at its log entry (logBuild).
func (b *Builder) awaitEnd(key string) chan builds.BuildLogEntry {
	ch := make(chan builds.BuildLogEntry, 1)
	b.mu.Lock()
	if b.stepWaits == nil {
		b.stepWaits = map[string][]chan builds.BuildLogEntry{}
	}
	b.stepWaits[key] = append(b.stepWaits[key], ch)
	b.mu.Unlock()
	return ch
}

func (b *Builder) dropEnd(key string, ch chan builds.BuildLogEntry) {
	b.mu.Lock()
	defer b.mu.Unlock()
	for i, c := range b.stepWaits[key] {
		if c == ch {
			b.stepWaits[key] = append(b.stepWaits[key][:i], b.stepWaits[key][i+1:]...)
			break
		}
	}
	if len(b.stepWaits[key]) == 0 {
		delete(b.stepWaits, key)
	}
}

// stepEnded tells the step asks waiting for a build that its end was logged.
func (b *Builder) stepEnded(e builds.BuildLogEntry) {
	if e.Event != builds.BuildEndedEvent {
		return
	}
	key, err := builds.BuilderBuildKey(e.Module, e.FP)
	if err != nil {
		return
	}
	b.mu.Lock()
	chans := append([]chan builds.BuildLogEntry(nil), b.stepWaits[key]...)
	b.mu.Unlock()
	for _, ch := range chans {
		select {
		case ch <- e:
		default:
		}
	}
}